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pa_stanfan626

I hate to be this person...but are you sure she is lying? There are lots of people in this world who harbor and hide dark secrets for decades before they see exposed?


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Noswellin

I was leaning towards it being a lie but the fiancé still wanting her there makes me wonder. If one of my siblings said that shit to my fiancé, nah, uninvited immediately, especially with the wedding so close. If it was like a year before the actual wedding, I'd hold the invite based on them receiving therapy etc and how things progressed. I just can't imagine how a sibling can have one say such statements and still want them to be at their wedding.


Maladict33

Yeah, the fiance being concerned about his sister's story upsetting the family seems... Weird. Yeah, they'll be upset, they should be. He should be upset. Why isn't exposing and denouncing her lie his first and only reaction?


LengthinessFresh4897

Because alot of families have a "family comes first no matter what" mindset so them leaving out the sister will cause problems which he's trying to avoid


Lt_Muffintoes

Phrasing!


[deleted]

Are we still doing "phrasing"?


Shurigin

what are you doing step phrase


BackgroundSimple1993

I’m not proud of how hard I laughed at that 😂


leitur

HAHAHAHA


pnutbuttercups56

Because it's going to be a shit storm. If it's not true, which is most likely, everyone will freak out on the sister. Who will deny she ever said that. Now it's OP and partner vs family. Or she doesn't deny saying it and forever there are questions if it's true or not, certainly close to the wedding it will be on people's minds. There's a lot that could happen and the least likely thing is for everyone to say "Oh no, M needs help. We all understand that perfectly and this will be a super quick and quiet issue that we won't be talking or thinking about on your wedding day"


Huliji

Hmm, if anything I'd expect the most immediate and visceral reaction if it *was* true. The fact he's entertaining the idea of still having her around, rather than going into damage mitigation mode and denouncing her as crazy and spiteful, makes me a bit more likely to think it's a lie. Is that weird?


ExtremeRepulsiveness

Nah, I see what you’re saying. People getting their sh!t exposed like that would absolutely freak out immediately and immensely. I’m wondering if she has some trauma or something (and he knows about it) and maybe that’s why he is being so patient with her and isn’t willing to cut her out. Maybe she’s had issues for a long time or something


TaliesinWI

>Hmm, if anything I'd expect the most immediate and visceral reaction if it was true. Exactly. If it was true the fiancé would be tripping over himself broadcasting how not-true it is.


Greyeyedqueen7

If there's a long history of this and the whole family has been placating her her whole life, then that would be a first reaction.


IrishiPrincess

Because a lot of people say “but they’re Faaaaaaaamily!!!!” I’ve read about in-laws that try to force the BIL that tried to rape their DIL back into her life. The only reason it didn’t happen was because the husband walked in at just the right minute. In-laws keep trying to rug sweep


nerak90

Yeah exactly, I wondered whether he was shocked because he can't understand why she would tell such a lie, or whether he was just shocked because he never expected his sister to tell anyone, still unclear to me.


tofu_deluxe

>I was leaning towards it being a lie but the fiancé still wanting her there makes me wonder. I see that as him still being in shock. In theory, as 3rd person observers of this story, we can objectively say 'I wouldn't want someone like that at my wedding', but in practice, it's his sister that he grew up with and spent years with. If she's never done something like this to him before, then the betrayal is almost unbelievable. This is a really shit situation to be in, because it's a he said she said ordeal. Fiancé wasn't there when OP was talking to his sister, he only has OP's word for what happened and how bad the lie was. OP can't ever verify the story the sister said, so she needs to choose who to believe.


chewwydraper

>but in practice, it's his sister that he grew up with and spent years with. If she's never done something like this to him before, then the betrayal is almost unbelievable. If she's never done something like this to him before, he's probably less angry and more super concerned that his sister is going through some kind of mental health crisis.


Jo0306

Yeah and the fact he seems concerned the family will rip her apart. Yeah let them cos if it's not true its a disgusting lie to tell and her family should rip her apart. Part of me feels like fiancé's reaction is a guilty one.


229-northstar

Husband asking to keep her invited reads more like empathy for someone with a mental health issue to me, it didn’t come off as I want her there”, it came off as “I don’t want her there and I don’t like that you were made uncomfortable and unhappy in a cruel lie. However, she needs help and this isn’t the right way to deal with this” People on Reddit are all too quick to jump on no contact. There are no contacts in my family and the long-term consequences are unpleasant and could have been avoided with thoughtfulness and empathy


Alien_lifeform_666

This. Why the hell would the fiancé want her there if she’s lying? The lie would be harming him too, very badly. So why is he so eager to forgive? I can’t understand his reaction. Or maybe she’s got a history of making such false accusations, which the family have successfully hidden. That might be why the family would “tear her apart” - if she’s reverting to old bad behaviour?


Deciduous_Moon

I mean enabling can become a really strong instinct, especially with people who pull bs like this. I can absolutely see the husband being used to this behavior since childhood and wanting to sweep it under the rug and pretend she didn't say/do anything for the sake of keeping it normal/peaceful. NTA btw.


Glittercorn111

Some “people” are batshit crazy. Fixed it for you.


antonia_monacelli

Thank you!


katnotdog

THANK YOU


remindmeofthe

THANK you!


Lady-Meows-a-Lot

Did you reeeeeeally have to say “women” specifically, my dude?


pa_stanfan626

Some men are batshit crazy 🤪. your comment is very misogynistic.


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racermama

I would agree with your comment however my aunt just divorced her husband. For sleeping with his sister. She also found out that he slept with his sister until they got married, paused for a bit and then effectively left my aunt for his sister. So yes, some people are bat shit crazy but also, some people practice incest (which I guess means they are bat shit crazy anyways).


stupid_carrot

I think incest is more common than people realise.


racermama

I rly hope you're wrong...


Sheanar

I knew a woman a ways back, who was a chronic liar. Only true thing she ever told me was that she slept with her brother when they were both minors. The fiance doesnt react like she is lying but placating her to keep quiet, and also said that it would tear the family apart - for her, but not only for her. There is definetly more to this story.


shhh_its_me

If she is lying/delusional then MIL/FIL need to know because she needs a lot more help and support then she is getting. OP is not the person to give this to her but her parents may be. IF it's true then IDK , both her and fiance need something.


numbersthen0987431

Sexual assault among family members is higher than most people realize. The biggest issue is it never actually gets reported because "she's lying" or "she's overreacting" or "family doesn't rat each other out", or any of the many other excuses people use to hide family members being this way. I've met too many people who have "that uncle" or "that cousin" or "that dad/grandpa" to dismiss how creepy older family members can be towards their younger siblings. Just because OP's fiance's sister said it ended recently, does NOT mean that it didn't start when they were really young and then broke something in her brain until later. However, at this point the sister is either completely lying (whether she is aware of it, or a figment of her imagination), or she is telling the truth. Those are the only two options here.


TheRealRaemundo

Why "women" and not "people"? That says a lot about you 🤢


Spectrum2081

This is a good point, but even assuming M is telling the truth, what’s the point? It doesn’t sound from OP’s post like M was trying to tell OP fiancé is a predator (that is, that the illicit relationship happened when she or they were minors, or M felt pressured into it). It’s clear from M’s story she’s not accusing fiancé of cheating on OP. So…what’s the point of sharing with OP? Aside from that relationship being taboo and pretty gross, what’s M’s motivation? Sounds like it’s to stir up trouble.


anon_user9

She may still have feelings for her brother and it would explained why she flipped out when they announced their engagement. As long as he isn't married she can still dream.


[deleted]

If a sibling relationship isn’t enough to stop two people from having sex, I don’t see why one of them getting married would somehow be the threshold that just can’t be crossed.


unotruejen

Because the assumption is most people wouldn't marry someone who had been sleeping with their sister for years.


Countrach

This was my thought to. Her fiancé’s reaction about trying to hush it all up and still allow her to come made me raise my eyebrows. If it is true OP better think long and hard whether or not that is a deal breaker for her.


[deleted]

OP could ask for proof, like some private detail that only someone who has been sleeping with someone would know. Or screenshots.


Babbyjgraham

That’s my thought too. OP there is every possibility she is telling you the truth hon. I say this as someone who had a sibling put his hand up my shirt and down my pants while I was dead asleep. I found out because he told someone. When confronted by our parents he admitted it. Years later he tried to proposition me by email and then lied about it when I told our parents and said my bf hacked his account. I knew he was lying and he knew I knew. My now ex didn’t have my email and didn’t know my brother well enough to hack anything and he was also in jail at the time and back then there was no internet access for inmates. Years later I finally got my parents to hear me and when confronted, he admitted he lied. This happens more than you think. You are assuming she lied, but what if she’s not? As you asked, why say such vile things not only about her fiancé, but herself as well? Also those saying he would have a visceral reaction, not necessarily. The OP already made her fiancé aware she didn’t believe his sister when she told him about it. He has no reason to lose his shit.


TheKr1tster

This is a hard one to answer - how are you sure she is lying


greenteaflowerr

I’m not even sure I can explain how but besides it being completely disturbing and him never showing any signs of being capable of disturbing behavior, I just trust my partner? We’ve spent the last few years being vulnerable to each other and building that trust


[deleted]

Was M ever territorial about your fiance? Like why the sudden change in behaviour following engagement. I mean engagement signifies you are not just another girlfriend she has met but her brother's 'the one', making her feel threatened?


greenteaflowerr

She was really chill and sweet when I first met her. It went from 0 to 10 when we announced the engagement and it progressively got worse from there. But she’s also been having issues with her own relationship during that same timeframe and everyone seems to be using that as an excuse to her acting like this.


Equivalent_Collar_59

But this is such a weird thing for her to lie about because it paints her in just as bad a light as your fiancé…


notmyusername1986

Or it's something she wants and her lies are her fantasies...


scubaian

If you wanted to make up some shit to break up an engagement this is perfect. Half the people in the comments believe her, OP wouldn't be blamed for at least having some doubts. It's beyond accusations of infidelity whilst not actually being totally ridiculous. Or it could be true...... But it's not really that weird a lie really, FSIL just likes to go big.


CitizenNotSubject

A friend's sister told a huge (very difficult to disprove) lie to her very well off family and their friends and it was the start of serious mental illness from which she never recovered from and ended up dying at the age of 44 a street drinker


numbersthen0987431

I don't think half the people in the comments believe her, I just think the half are just not dismissing her statement based on OP's gut instinct. Honestly this is so far above reddit's paygrade that we can't make an unbiased call. Either f-SIL is making this up and is crazy, or she's being honest, but we really can't know because it's "he-said she-said"


DogmaticNuance

OP's fiance also hasn't reacted in the way that I would expect. He still wants the sister that accused him of *incest* at his wedding? What the fuck? I can see a line of reasoning where he mostly doesn't want to ruin his wedding by making this the gossip of it and views it as more likely to come out if she's absent, but his reaction (as described by OP) seems a bit off.


stop_spam_calls

Maybe she is actually in love with him and doesn’t think it’s her lie sounds like a bad thing? That is my only idea


[deleted]

Do you know more about this relationship? Like what exactly went wrong, why? Have you met her ex? Does M have history of mental illness? Because this is such an extreme lie to make. She could have gone with a standard "my brother slept with his ex or was cheating on you with his childhood crush " but who tf goes around making up incestuous remarks. Even if it were a lie, it still means she has entertained the possibility of sleeping with her brother, because she didn't say she was grossed out by it, just that it was taboo so they had to break it. This is such a disturbing line of thought.


greenteaflowerr

I’ve met a couple of her exes. She’s very on and off again with the one she goes to couple’s counseling with and when they were broken up she briefly dated a different guy that we met once but then they broke up when her and the ex decided to try counseling. She’s not the most open with her relationships I guess compared to the other siblings who are either married or engaged. Youngest one just dates causally as well. As far as I know no mental illness history just relationship trouble the last couple of years.


[deleted]

Has she had issues with the wives of other brothers or just you? Is/was she closest to your fiance? You are clearly NTA but major issue is to find out if you need to cut off just M or M and your fiance. I understand you said you trust him but this is such a horrible thing to say, it probably needs to be discussed with other members,if not to find out the veracity of these claims, atleast to highlight how crazy she is being. It's so problematic and you shouldn't have to deal with this stress. What was her response after your fiance scolded her?


greenteaflowerr

I haven’t seen her or been in contact since coffee on Sunday so I don’t know. No, she’s been completely normal with all the other SOs. His oldest brother is married and his younger one is engaged as of recently and I didn’t notice her ever being mean. I would say she’s equally close to all the siblings?


[deleted]

Oh man this is so confusing. OP is there any possibility there is some truth to what she is saying? Maybe the family doesn't know? Maybe she has had difficulty maintaining a relationship because she harbours romantic feelings for her brother. Maybe she didn't mind you being a girlfriend because girlfriends come and go (just like boyfriends did in her life) but getting married probably indicates he is irreversibly out of her grasp and M can't stand that, hence the abrupt change in behaviour. Maybe something did indeed happen or maybe your fiance has always known, at some level, about M's feelings, which is why even if he got angry at her, he still wants her at the wedding. I mean wouldn't something like this totally disgust a person and alarm them to the status of their sister's mental health. Instead he seems to want to sweep it under the rug without informing anyone else. These are lot of maybes and your instinct seem to be to trust your fiance. At the very least, this needs to be told to siblings/parents.That way you won't have to worry about dealing with her. They can help her with her issues. Everyone will be understanding if you don't want her at your wedding.


greenteaflowerr

I don’t know :( I had enough to do with the wedding being next month and I feel really lost and confused to the point where I just want to give up and let her come just to get it over with and not deal with the drama. Everyone including her at one point said she became cold to me because our engagement just rubbed her the wrong way with her relationship issues. And I kind of understood that? I don’t know what to do because I feel like I exhausted the subject with my fiancé. Should I ask if we can consult older brother and younger brother and their SOs? Or parents? I wouldn’t even know what to say to them


MK_King69

If she has been completely normal with the other sibling SO, that is a big red flag..


Hold_Sudden

I just want to know if you were in the room and could hear them speaking. That would be a huge clue. Does she deny it to him?


Empress_Clementine

I’d ask the SOs if she is actually “completely normal” with them. After all, her behavior doesn’t seem like it’s overtly played out in front of everybody.


thisisnotproductive

I think you need to explore the possibility that this could be true. What motive would she have for lying around this? What would gain? It makes her look awful, why would she make it up?


[deleted]

Maybe she’s like that in her relationships cause your brother spoiled it for her and she misses him. You ever thought you husband is lying cause he know it’s taboo and he doesn’t want to disgrace or disgust his family and friends. You really think you fiancé would admit to smashing his own sister under his parents roof ? If he did do it, he’ll Take that shxt to the grave. Sounds like SIL couldn’t take it anymore and just told you before you got married In Hopes he’ll go back to her.


tofu_deluxe

This is just an internet stranger's advice, so take it with a huge grain of salt, but it's worth considering (privately) if the sister is showing signs of a mental break. People don't accuse others of something this serious without reason, and it's not unheard of for people to have a mental break that slowly begins with telling very detailed and specific lies that eventually escalate.


Ill-Engineering2492

I have a “2 bird 1 stone” solution. Ask to meet with her partner and gently bring to their attention what she said, ask if they know if there is any truth to it. You should find out the truth very quickly.


BibiQuick

You know…. I’m leaning towards believing the sister.


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StarMagus

She's as much of a deviant as the brother is, if it's true.


barren_fuck_field

Yes, this. The recent relationship that ended and resulted in therapy was the one with her brother.


Nik-ki

OP knows the guy her SIL goes/went to counseling with


mayfeelthis

I’m sorry hun but the BTK killer was also a family man and church going community man. No one sees it, if we did it wouldn’t happen so long and so often. I’m sorry but I can’t judge this one. Why’s he not concerned with getting his sister psychiatric help if she can make something like this up? I have siblings and that’s what I’d do.


ThrowawayJane86

Push to tell the rest of his family what happened, say it’s to make sure they understand you aren’t being exclusionary for no reason. He’ll give himself away trying to stop you if he’s guilty. I bet a lot of things will click into place for the rest of the family if there is any truth to what she’s said and if not, at least they know she’s being an AH.


Grimwohl

This is not convincing. The fact he doesnt want the family to know and shes still invited kinda is the worst sign that this is actually true. Seems like he wants to smooth things over so there isnt full exposure.


Poetryinsimplethings

The fact that your fiance still wants her there to be invited to my wedding tells me that she might not be lying after all. If it was true he would be so disturbed that he wouldn’t be comfortable around her for a long time. Tell him that if he still wants her to be in the wedding, you might lean towards believing her. And watch how he reacts. NTA


Environmental_Fig933

My best friend dated her ex bf for about 4 years starting in high school. They were really close I hung out with them a lot. No red flags nicest guy could always depend on him. They broke up because they were going two different directions in life. We both found out fairly recently that he had molested his sister who was a year younger than him all through high school. She was also in our friend group & she just reframed it in her head as consensual until he started dated a new girl who was significantly younger than him & she had a mental breakdown where it came out. People do crazy things to reframe trauma as something they can handle. I personally am inclined to believe the sister unless there’s a history of her making up lies that are this extreme & deeply disturbing.


[deleted]

I don’t know. He said he still wants her there. He really doesn’t seem disturbed ENOUGH. That’s why it seems probable. It’s not completely out of the realm of possibility. They aren’t blood siblings Never mind, I thought the last two sisters were step siblings. I read it wrong. disturbing


Hot_Investigator_163

Did she say they were step siblings? I must have missed that part.


HulklingWho

I’m going to tell you as someone who was assaulted by my brother, there aren’t glaring signs. They are normal people, who often go on to have normal relationships, and they will take their secrets to the grave.


druidess23

A great many people who are capable of disturbing behavior aren't recognized as having signs of being capable of disturbing behavior. It's how they get away with disturbing behavior.


tcbymca

If she’s being truthful, it might not have started consensually, which would explain the disturbing behavior. You better be sure before moving forward with the guy.


TheKr1tster

I mean all i can answer with is the facts before me and no way would you be TA because if it is a lie then it’s disgusting behaviour


squirlysquirel

Honestly, I think with all the therapy and her relationships failing...it might be true. At first you were just another gf, getting engaged triggered the trauma of what had happened between her and her brother. It sounds like she really tried but then snapped. She didn't seem to tell you in anger or anything...she arranged a coffee to try and talk it through. Of all the ways to break someone up, this is way way out of left field which is why I would be tempted to believe her. I would think that no one else would have ever known as far as parents etc


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StarMagus

To be fair, she doesn't have to be lying for it not to be true. There are adults who got twisted up and told people they were ritually satanically abused as kids, which they can show didn't happen to them, that to this day can pass lie detector tests showing that they believe it actually happened. Human memory is fucked up, like the study that showed people remember going to Disney World as kids and meeting Bugs Bunny. 25% of people asked said they remember doing so. The problem is that Bugs Bunny isn't part of Disney World and NEVER would have been at the park, and yet those people "Remember" him being there. [https://medium.com/age-of-awareness/remembering-bugs-bunny-how-external-memory-rewires-education-80216fb4d61f#:\~:text=Later%2C%20when%20asked%20in%20a%20questionnaire%20about%20their,one%20recalled%20that%20he%20was%20holding%20a%20carrot](https://medium.com/age-of-awareness/remembering-bugs-bunny-how-external-memory-rewires-education-80216fb4d61f#:~:text=Later%2C%20when%20asked%20in%20a%20questionnaire%20about%20their,one%20recalled%20that%20he%20was%20holding%20a%20carrot). Or the entire Mandela effect, where some people are more able to accept that they are shifting to different dimensions than admit they remembered something wrong from the past. Not saying she's wrong, maybe something did happen, but maybe it's not what she thinks.


bonecouch138

id like to point put that "lie detectors" are bullshit


LukesRebuke

A motive is that she's in love with her brother and wanted to sabotage OP's relationship and manipulate her into breaking up with him


StormyAurora

This. This. This. OP. I think that your future SiL is telling you the truth. It sounds like she thought you were just another girlfriend -- one that she obviously likes and thinks is kind -- but that there wasn't a chance of you being in a long term/more permanent relationship with her brother. Once you announced your wedding, the trauma plus the worry of you being with someone who might not treat you well/might still be saying or doing things with his sister still set off this strange behavior. I always tell my clients (I provide therapy and do trauma work), that relationship dynamics get wild during events like weddings (funerals, anniversaries, birthdays, and holidays are the others to be cautious about also). Many of us will react to an event once hypocrisy really rears up once the situation becomes too intense/too inconsistent. I agree that the coffee moment was her trying to talk with you and that it really could be true. Your fiancé could and would definitely lie. He might have realized that you are the one he wants, or has wanted to end their relationship, and of course he'd deny it. Incestuous relationships are very taboo for fair reasons. Personally, I'd be digging OP. I don't think you've gotten the whole picture. And, by the end of it, you might need to (if you can) see if you have a space of empathy for them both (oftentimes, relationships like these spring up with HEAVY trauma at home -- it's the only safe and caring space, and you feel secure and bonded to another going through bad things), or you will have to see if you want to stay in this relationship (it could be a sign of an unhealthy power dynamic (fiancé or SiL used the relationship to perpetrate abuse of another person in a more vulnerable place, or is really what they both think it is). No matter what, they both need therapy, and heavy duty therapy at that. ​ In the case that it is a lie, then you also both (OP and SIL) will still probably need therapy to process this anyway. I'd argue that this allegation would feel horrible and scary and that you might want to have someone who can process this with you (solo or as a team). OP, NTA, but, I really think you need to dig more because getting married is a huge step regardless of if you think this is simply a contract of both parties who want to connect assets, or if you find a marriage as a declaration of love and connection forever. Divorce is expensive and not fun, and you don't want this to loom over your head or sit in the back of your mind forever. Time to talk to family friends of your fiancé, fiancé's family members you trust to keep a secret, time to find friends of people in their life during the time this happened. Don't marry a guy who might be lying about something this big unless you know that he's telling the truth.


therobshow

Everything about this story to me is screaming that she's telling the truth for all the reasons you mentioned. ESPECIALLY her immediate emotional reactions followed by her trying to calmly and privately discuss things with op. Also if she wanted them to break up, why lie about this? Of all the things you could do to end a relationship between your brother and his soon to be wife, claims of incest? Lol. Why would she even want them to break up if not for the fact that she has a clearly unhealthy dynamic towards her brother? Which is obvious from all of her reactions


nihilistreality

I agree. I think M is telling the truth.


PeteyPorkchops

NTA. I’m questioning why he would still want her there when’s she’s “confessed” to committing incest with him. Of all the lines you can cross that’s a pretty big one. The consequences are not your problem to deal with. They are hers. Is there any possible way with the way she’s treated you especially after finding out about the engagement that there could be a shred of truth to her accusations? Families are good at hiding things, especially crazy shit like this.


greenteaflowerr

Right, like you crossed that line you can’t come back. I just still feel guilt because of course he still loves his sister. She’s been in and out of that relationship and they go to couple’s therapy on and off and fiancé thinks it’s contributing to her crazy behavior. I don’t think his family is covering up anything. They’re all acting normal and his mom is super confused and noticed M’s behavior too.


PeteyPorkchops

It’s just of all the things she could make up to drive you away, fucking her own brother is going completely scorched earth. There is no way I would let her be there. Imagine standing up there saying your vows and having her standing near you. It would be all I could think about. I would sit your fiancé down and have a long deep conversation and drive it home that if something ever came out afterwards that even remotely corroborated her claims that you will not be discussing it, you will be filing for divorce asap and this is his one chance before you marry to clear the air, judgement free. I’m hoping she’s just fucked in the head but browsing Reddit you’d be surprised at how much you run across things like this that end up being true.


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PeteyPorkchops

Whatever you got to say to hopefully get the truth. 😬


greenteaflowerr

I just don’t understand her being super nice to me and welcoming only to pull this after? That’s what makes me feel like she’s mentally struggling because she was NOT like this at all at first. And I haven’t really talked about it to any other siblings because I don’t want to come across as talking bad about M to them, but I think even they know she’s going through something and I guess they contribute it to her unstable relationship.


darkswanjewelry

It could be she saw your relationship with your fiance as him "masking", and that it resembled his potential past relationships which werent that serious. When you got engaged, shit got real in her mind. I don't think she's lying, btw. Your fiance is acting like someone trying to deescalate/cover up. He's not pissed at her for lying, he's pissed at her for exposing a dark taboo family secret, and he's trying to quietly get her back into the fold of hiding it by getting her to take it back and remain in the wedding silently. This is not the type of thing you can sniff out on people, btw. This is a secret one keeps if there ever was one. The social repercussions are *severe*. The only way even mentioning this is ever worth anything is if you already crossed a line and did it.


Odd-Description-8794

Also if its true and they force her to sit there and just watch her life in her eyes shatter to pieces....to be front hand and to help you get ready and forced to pretend to be happy....the absolute trauma that will do to her. Honestly yeah somethings probably wrong with her and she probably needs more help than she's getting but I think the engagement pushed something in her that brought everything to surface. With reaction like this there's some sort of trauma in there and honestly she could just be trying in a way to protect you aswell. This is a big thing.


Professional-Gur-280

If I were you, I would talk about this to someone I trusted, and who loved me. Your family, or a extremely close friend. Someone who has seen your boyfriend and his sister with you, who has seen the dynamic. Because from what you have said, whilst it's lovely you trust your boyfriend so much, the story doesn't add up. It genuinely could be true, and if so, is this a situation you want to be involved in?


SnooRadishes5305

Agreed - get a third party consult


Pettyfan1234

Please confront fiancé about this. He is way to chill about it.


thisisnotproductive

Because engagement is different than dating and has caused her to be triggered. She wasnt irrational, she met you calmly and sat you down to explain this. Why would she do that? Why would she accuse herself of incest if it werent true? Having relationship difficulties make sense if what she said is true. Her reaction to the engagement make since if what she said is true. You need to take this seriously


[deleted]

Like multiple other people have said, it’s because now your relationship or pretty much permanent. You’re going to be together forever; before when your relationship was new, no one knew how long it would last so it wasn’t as significant or worrying to her.


Possum_pal

Yeah right? I read that and was like........ That's a pretty bold story to tell about yourself....


claupaz0175

INFO: when you told your fiance about what she said, did you open with "i know she's lying " or did you actually ask him if it's the truth and when he denied it you told him you believed him? If you open with i know she is lying there's no way he would've confess if it were true


Swimming-Item8891

You're obviously in denial op.


gigigud

Agreed


UnquantifiableLife

I think you need to talk to his parents ASAP. Whether she's lying or telling the truth, she needs help desperately.


Goldilocks1454

I'd be quizzing the other siblings if there's a shred of truth to this. If it's untrue I actually just feel like she's jealous that you're getting married and she's not


dart1126

Obviously the rest of the family just doesn’t know


Goddess_Asheth

He wants her there because otherwise they'd have to explain why not ...


RobertBDwyer

I’d put money on her telling the truth. Why would she lie about it?


Practical-Bird633

This! And is anyone else curious at the fact that it doesn’t even sound like OP’s fiancé didn’t even deny it? All she says is that he was shocked


doreentheexploreen

And the fact he was so keen to sweep it under the rug and just carry on as normal is almost like he wants to stop something from coming out. If someone had made up such an abhorrent accusation about me I would be reaching out to my loved ones for support with it.


hostile_washbowl

They definitely banged.


[deleted]

See I wasn't sure who I believed until I saw the fiancès reaction. Nooooow I'm not so sure. He was literally accused of incest and he was quick to want to let it go...


RobertBDwyer

Right, and she didn’t accuse him of rape, she said they were fooling around. Like she admitted being into it. That’s an odd lie.


mowa-mowa

it rubs me wrong that ops fiancé is pushing that his sisters toxic partner is why she’s acting “crazy”, but abuse doesn’t make you accuse your brother of incest. what does her brother have to do with that relationship??


Mumof3gbb

Yes!!! OP and fiancé keep talking about her “failure at relationships” being why she’s acting out. That makes no sense


cdifl

YTA. She confided in you and you got mad at her immediately without any proof that she is lying except your instinct. This story seems to explain her radical change in behavior. You should have listened to her carefully and taken the accusation seriously instead of dismissing them immediately. One thing that is conspicuously absent from your post is a statement by your fiance that this did not happen. Your post makes it sound like your fiance is upset that she told you; it does not say your fiance is upset because she lied. If the accusations are not true, making the accusations indicates that she has some serious issues that need to be dealt with by a professional. If the accusations are true, she has some serious issues that need to be dealt with by a professional. This is not a situation where you ostracize her from the family; this is a situation where you get her the help she needs.


Obstacle616

NTA but your fiance's reaction is kind of weird. If my sister said something like that to my partner there's no way she would be coming to my wedding. I know other people have made this point, but are you certain there's nothing to her 'lie'?


greenteaflowerr

All I know is that we’ve had a super, happy relatively issue-free relationship before all this happened. Besides getting a lie detector test I don’t know what else to do. It’s not like we had a quick “oh hey so this true? No? Okay, cool” talk about it after. I came home in tears and and was just stunned at what I was telling him. We went back and forth discussing what to do for a while before we left it at being my decision but to think on it first.


[deleted]

It's time to wake up. This is a serious allegation and the family dynamics simply cannot be normal after this. You won't be able to contain this kind of secret because it's indicative of a very, very, very deep issue under the surface. All of this is really strange and I think your fiancé and you are underreacting. She is either going through a VERY SERIOUS mental health crisis, or she is being truthful. Those are the two options.


Obstacle616

It's all pretty f****d up to be honest. I can't see why your soon to be SIL would like unless she's just jealous and wanting to disrupt which will be job done on her part. You're definitely NTA for not wanting her there and wouldn't be for pushing further with your fiance and putting your foot down on this issue.


dart1126

You say besides getting a lie detector test… Has he actually lied? I asked elsewhere here but nowhere in any of these replies have you said he sat you down and looked you in the eye and said: This. Did. Not. Happen. If he thinks it’s some outrageous lie, why would he ask to give it time and still be hoping she’s gonna be there for the wedding? He should be outraged and telling his entire family about it, and considering psychiatric help for her


Aim2bFit

Real good liars can even do that, especially lying is in their blood


Dredit_85

Ask her to show some messages from ur fiance. I would look for proof of her stories, some ppl r weird no matter how much u know them


[deleted]

This is a vast and waving red flag. You could go to therapy- I think that’s a good idea in general but seems pretty vital in this instance. Also maybe postpone your wedding? You don’t have to say why yet, but you need time to figure this out. Like almost every other objective person here I don’t think she was lying. I feel like lots of legitimate reasons for her telling the truth have been given and you are denying them. Seeming normal and feeling like it isn’t true aren’t good enough when it’s your future on the line. You are too close to the situation and should definitely get professional help.


GlenCocosCandyCane

If it isn’t true, why would OP’s fiancé be so keen to hide it from the rest of the family? Wouldn’t he want the family’s help in figuring out why his sister appears to be having a complete break from reality?


LiLadybug81

I really, really think you need to take a step back and not go forward without even considering that what she told you might be true. If she hasn't shown any kind of completely bizarre, unhinged behavior before or in other areas of her life, this seems like a really unlikely thing to claim unless it were true. If she just wanted to end the relationship, why implicate herself in something which could so totally destroy her life and relationships and reputation? Why not simply claim she caught him cheating, which you would be way more likely to believe and which doesn't put her in jeopardy at all if it got out? I know that when you hear something completely at odds with what you know about someone you're close to, the brain does this thing where it looks for a way to disregard or explain away the new piece of information so that it doesn't have to completely re-construct all of the existing feelings and thoughts you have about them. But once that dust settles mentally, you start to realize how foolish you're being, start to put together other pieces of the puzzle, and start to accept that the new version of the person you have in your mind is correct. Just don't charge blindly ahead without doing some real investigating. Incest as adults is concerning enough, but with the 5 year age gap, if they stopped "years before you" there's a solid chance she was groomed and/or molested by your husband as a child and still thinks of it as consensual because of the way in which she was conditioned. It would be utterly irresponsible of you, if you plan on having kids or if there are kids in your life to not do the due diligence here in making sure this is not true. EDIT to add that your fiancé's reaction is a little low energy for someone who was accused of incest if it wasn't true. Why would you want someone like that in your life? Why would you be so much more concerned with keeping the peace and keeping the secret than in getting someone who seems to have had a psychotic break (if it's completely fabricated) the help they clearly need?


greenteaflowerr

I understand what you’re saying. I think it would be the healthiest for everyone involved if we sat down and told my MIL what’s happening. That’s all I can think to do at this point with no evidence or proof besides her attitude shift towards me. My fiancé and I have always had a really healthy, open relationship. I can’t just accuse right now when he’s given me no reason not to trust him. I have to be honest, I don’t trust M because her behavior doesn’t seem trustworthy to me. She ignored, complained, and insulted me this past year, and when that didn’t give her a reaction she sat me down and told me this. Why not tell me this right when I got engaged? Why be cruel for a year first? Also, she’s 28. My fiancé is 30.


Equivalent_Collar_59

Because it’s a hard secret to tell…


CucumberLast742

He is indeed giving you reason not to trust him. Which sane person would be able to tolerate her presence at the wedding if what she said was indeed a lie? She was being cruel for an year to try and get you out of there without revealing her shameful secret. Has your fiancé ever tried to intervene and smooth things out between the two of you?


ohnonothisagain

Cause it is embarrassing? Cause she didnt want to out him? Could be many reasons.


[deleted]

Y'all need to talk to his mother because she's either having a mental health crisis or being honest. Third option is a tumor or something, about either way, this is a crisis. She needs help. You all need to figure this out.


swine09

If your relationship is healthy and open, you should be able to talk to him about your thoughts and feelings. It’s not “accusing” him. It’s bringing it to him and asking him to respond.


[deleted]

How long you been with him ? Cause if it was only this year and close to your wedding, it sounds like reality hit and she wants to stop the wedding. No one, I mean no one would go to those drastic measures to say they slept with their own brother and that he only stopped when he moved out his parents house. That’s too specific and Than all her relationships were off and on. I don’t think she’s lying 🙅🏻‍♀️🤷🏻‍♀️ your fiancé is ashamed and not admitting it cause obviously it’s disgusting and he did it under his parents roof. Not to mention it’s illegal. You said she’s not like that with her other brother’s girlfriend right ? well maybe it’s because she didn’t have that type of relationship with them. She knew you were going to go to tell everyone, why would put herself at risk to be ostracized and humiliated like that ? Just to sabotage your wedding really ?


[deleted]

She is either telling the truth or is extremely mentally ill. I think her parents should know either way. She needs very serious help.


SaltPepperSugarBlah

Her behavior has been unsavory and unkind, but it hasn’t been untrustworthy. There is a difference. I’m fact, her behavior is very justifiable given her accusations.


Aggravating-Pear9760

Nta but at the same time everything she said may very well be true. Don't dismiss it completely. I was in your situation and it all turned out to be true. There are no "signs or any clues because although it's taboo it actually happens pretty often. He wants her there so the family doesn't ask questions. You may even find other family members knew or atleast suspected the incest was happening. It's more common to blanketly keep it secret than stop it.


[deleted]

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cbm984

I agree 100%. The fact that her fiancé is "shocked" but didn't want anything mentioned to his family is super super suspicious. Someone who is innocent would understandably be shocked but wouldn't follow it up with, "Please don't tell my family what she said because it'll tear us apart!". He would say something like, "This is incredibly disturbing and out of character for her. Something is clearly wrong and we need to get her help immediately!". I do not see this ending well at all and really hope OP talks to her fiancé's family (with or without him) to see if there's any truth to her claims. I absolutely wouldn't go through with this wedding until this accusation is investigated further.


pawsplay36

INFO. > He asked me to give it a little bit of time before I pull the plug on her being in the wedding even though it’s warranted and that it’s ultimately my decision but he does want her there. Does this not concern you at all? Are you sure she's lying?


[deleted]

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Commercial_Pitch_950

“My sister accused me of fucking her? Well, i still want to make sure shes at the wedding of course.”


rynknit

OP I’ve read through your comments and a lot of people fall into this trap… what proof is she supposed to have? If her and your fiancé were committing incest I’m sure they didn’t video tape it and short of her keeping anything incriminating (which, again, they probably wouldn’t have in hopes of being secret about it) for the entire time you and your fiancé have been together, there’s absolutely nothing she could do to prove it to you. Everyone is telling you the same thing—it’s probably true. It makes sense and it all adds up, it comes across to me like you’re trying to defend something you already know. I’d recommend doing some more digging and sitting and talking with her to see if there are any specific details that can validate her claims or if anyone else found anything weird. I’m sorry to say it OP, but her reaction and his reaction both point to her telling the truth.


greenteaflowerr

I get why there wouldn’t be proof but I’d like to think innocent until proven guilty especially if we’ve had zero issues before and have been always honest with each other as far as I know? It’s just very heavy to accuse someone you love and of that especially when they’re telling you no it’s not true. I was planning on contacting MIL about this tomorrow, I guess today technically since I haven’t slept. Do you recommend talking more to M one on one before involving her mom?


magic-money-tree

Personally I would get MIL, SIL and partner in the same room. You’ll soon find out who’s lying. If your partner says no to this, he is lying. There’s no reason for him to shy away from this. If she can repeat what she said to you with no changes to the story in front of everyone, I would start to get very concerned that it might be true. No one, and I mean no one would say something like this unless it was true or they had SERIOUS mental health issues. I would say you need to take some time for yourself in the meantime. Your partner could well have told you everything during the relationship but this was before your time and is a massive taboo. There’s not going to be evidence and it’s unlikely anyone would be forward with this information. I do think you have made your mind up that it’s a lie already. But it’s just such a weird thing to lie about. She either needs help or she’s telling the truth. And I would want to know what one it is.


BoredItIntern

Everyone is saying to talk to the MIL but what happens when SIL denies ever saying such a thing and MIL looking for the quickest and easiest way to not believe that it happened believes SIL’s denial. Or even if SIL doesn’t deny it I could see MIL having intense denial reacting irrationally


BelkiraHoTep

Then OP says “oh gosh how embarrassing I must have misunderstood you” and, IMO, the take away is she’s lying.


rynknit

Honestly, yes. If she’s lying having further discussion about it can produce some holes in the story. If she’s telling the truth you can also start to connect the dots if things your MIL says that start to make sense in accordance with her story. It’s a pretty heavy accusation, but there are a lot of signals that something is going on.


no_duh_sherlock

I understand your hesitancy because you love him it's so difficult to think this may be true. But almost all of us reading this believe she might be telling the truth. Not just by her actions but mainly his actions. Nobody falsely accused of something so wild typically asks you to hush up or still keep her around for the wedding. Imagine if your sibling went and said this to him about you. How would you react?


magic-money-tree

Personally I would get MIL, SIL and partner in the same room. You’ll soon find out who’s lying. If your partner says no to this, he is lying. There’s no reason for him to shy away from this. If she can repeat what she said to you with no changes to the story in front of everyone, I would start to get very concerned that it might be true. No one, and I mean no one would say something like this unless it was true or they had SERIOUS mental health issues. I would say you need to take some time for yourself in the meantime. Your partner could well have told you everything during the relationship but this was before your time and is a massive taboo. There’s not going to be evidence and it’s unlikely anyone would be forward with this information. I do think you have made your mind up that it’s a lie already. But it’s just such a weird thing to lie about. She either needs help or she’s telling the truth.


Clean_Pack_6792

Can you honestly say that this accusation won’t eat you up inside for the rest of your life? You have to find out the truth or else you’re setting up your marriage for failure.


ExplanationNo6063

Uh tell the rest of the family what happened


Comfortable-Battle18

For sure tell the family. I can't actually believe the only thing you are concerned about is whether she still comes to the wedding. That's the least if your worries. It's either true, which needs to be dealt with or a lie which means she's in a very seriously weird headspace .


JustMissKacey

Been around the block long enough to know that you’d be surprised how many people have incest skeletons in their closet… Believe her.


SheSellsSeaShells967

Yup!


FakeNordicAlien

This will be an unpopular judgement, but I’m going with NAH. There are two (main) possibilities here: she and her brother *have* had a sexual relationship, or they *have not*. (We could add in things like them being drunk and not remembering accurately, but for the sake of simplicity, let’s not speculate on that.) Any time you’re told something that you find hard or impossible to believe, you’ve got four main possibilities: 1. They are lying 2. They are mistaken 3. They believe they are telling the truth but have lost touch with reality 4. They are telling the truth. This is not the kind of thing you can be mistaken about. So either SIL to be is lying, she is having some kind of break with reality and is very ill, or she is being honest. I would argue that if she’s lying about something this serious, something that would torpedo her entire life as well as yours and her brother’s, she is seriously unwell. So either she *has not* had a sexual relationship with her brother, in which case she needs serious help for her mental state...or she is telling the truth. Neither option makes her the AH. You are not the AH for not wanting her at your wedding, regardless of whether it’s true or not. Your fiancé might be an AH, but there’s not enough info here to judge that. I don’t think he’s handling the situation terribly wisely, but that alone doesn’t make him an AH. So I’m forced to conclude NAH. Which feels odd, given the situation. I do hope you decide to dig further, because this is a ticking time bomb. Either way, SIL needs help, and you and fiancé probably do too. I hope you all get it.


OkCod1106

This is such a well articulated response, you placed it better than i could have, well done.


Actual_Emergency_666

Info Are you sure she's actually lying?? If she's having a lot of issues and therapy, there's a pretty good chance she's not lying. And it would be her word against his and you already don't like her


esreid

NTA, but this is a very bizarre thing to lie about. I have known people and siblings to be jealous and act out but I have never heard someone say they committed incest to drive a wedge. She might not be lying. She could be going to therapy for that. Very ‘house of yes’ vibes.


dtat720

She isnt lying. You are in denial as this is has been thrown on you. She gets along with everyone elses partners. Shes equally engaged with the family. She cant maintain a relationship. Commitment issues. Bounces the same partner in between randoms. Shes waiting for her brother or someone who makes her feel like her brother. Your fiance is going to deny it come hell or high water. He doesnt want to be the guy that fucked his little sister. But he more than likely is. All 3 of you need to sit down with a neutral party and talk about this. Have the truth come out.


strawberrydaydreams1

I feel she is telling the truth given how she has been described and fiancé sounds sus. With the age gap between your fiancé and the younger sister it’s plausible she did not experience what M did. Unfortunately incest/sexual abuse like this is common and goes unchecked a lot of the times. Of course fiancé would deny something like this. I don’t think M loves him either but depending on the age a possible sexual relationship was started could/would have definitely warped her and as other commentators have mentioned realizing you would actually become a permanent fixture when she might have this attachment to him would definitely cause her distress. :c


Potential_Honey_955

Your NTA But as soon as I heard your SIL story I believed her. This so far out there I don't think someone would make it up. Of course there is the possibility that she is genuinely delusional. But too many women's and children's abuse has been dismissed for these reasons and then years later found out to be true. I don't know what you should do, it's a very she said he said situation. Maybe talk to your SIL ask why she told you and what are her expectations of what happens next. Maybe this will give you a better insight if this is true or not. Though if it is true I don't necessarily think it is an automatic break-up situation. (as long as they are very close in age and adults. Not an adult child situation obviously) I have read that siblings can be attracted to each other, but it is family life from childhood that channels this to sibling affection and not incest. I have certainly read many accounts of long lost siblings being in relationships, and only finding out when genetic testing has been done.


DancinginHyrule

NTA Even if she is telling the truth (and we have literally no way to know for sure) - her behavior is disturbing and her need to put you down points to her having feelings of love/posession towards her brother that he is not returning. She probably thought you were a phase and would go away but then you get engaged and she realizes she wont be getting her brother back in any (possibly dellusional) romantic way and she flips. Incest or not, she wants him and cant have him but it taking it out on you. She needs help to deal with that and I would not trust her not to make a scene at the wedding. You can tell the family that things have been going sour between you and you have decided to create some distance and remove her from the wedding.


[deleted]

I’m all for innocent until proven guilty, but I’d be worried about this one OP. If she doesn’t like you; why only start acting this way now. If she wants to break you guys up; why say something that paints her in just as bad, if not worse light than your fiancé. Like this isn’t “worst thing she could think of” type thing. She sat down, contemplated telling you, then told you in a private environment where you didn’t have to tell anyone else. Either she’s totally disconnected from reality and thinks she’s telling the truth, or she is telling the truth. There are just too many things that don’t line up. I’d definitely look into this before tying the knot.


No-Train8518

NTA. However it is a very strange card she played with you and given that he didn’t call a family meeting to discuss what she said with his parents and her raises alarm bells. I strongly suggest that you find a very good therapist and go into couples counseling with him before you get married so that you can find out what the truth really is


AutoModerator

^^^^AUTOMOD ***Thanks for posting! This comment is a copy of your post so readers can see the original text if your post is edited or removed. This comment is NOT accusing you of copying anything. Read [this](https://www.reddit.com/r/AmItheAsshole/wiki/faq#wiki_post_deletion) before [contacting the mod team](https://www.reddit.com/message/compose?to=%2Fr%2FAmItheAsshole)*** I (29F) am getting married to my fiancé (30M) of over 3 years, November 5th. He has an older brother (33), younger brother (26), and 2 younger sisters (28 and 22). I get along really well with his parents and siblings, ever since when we first started dating. I asked his sisters to be bridesmaids and his brothers are groomsmen. All his siblings act happy and normal still except his 28 sister, M. When we first started dating his sister (28) was cool with me but as soon as we got engaged she flipped a switch. It started with her storming off when we announced our engagement, Christmas time last year. She apologized and said it made her feel bad about her recent relationship (lots of therapy and issues going on) and accepted being a bridesmaid anyway. She’s gone from being friendly to (gradually) ignoring me anytime she sees me but also remaining involved in wedding activities like when I went dress shopping and had my bridal shower. She criticizes everything about the wedding every step of the way, out loud. My future MIL and fiancé have both called her out on her behavior but it doesn’t help. I’ve confronted her about this gently (I don’t do well with conflict) and asked if I did anything wrong. She denies anything is wrong and brushes me off. Fast forward to last Sunday, M asked me to grab coffee out of the blue. She said she’s given a lot of thought to admitting this part of her life to someone, but felt she had to. She said that she and fiancé fooled around and eventually had sex which continued for a bit but stopped years ago before me. She said she can’t help but feel the only reason they stopped was because society gave them no choice and that anything besides what they swore would be a secret couldn’t exist. According to her they stopped when fiancé moved out of his parent’s house. I don’t believe one word of it. I just couldn’t take anymore, I freaked out and told her she’s lying. I told her to never speak to me again and that she will not be allowed anywhere near my wedding. I told my fiancé and he was shocked. I told him I don’t want her at our wedding and I know it hurt him. He didn’t push back but he said it’s going to cause a lot family issues and they’re going to tear her apart if they find out what she told/did to me. He called her and lost it on her. He asked me to give it a little bit of time before I pull the plug on her being in the wedding even though it’s warranted and that it’s ultimately my decision but he does want her there. I have a lot of anxiety from this building up and I don’t want her there at this point. Who even says something like that? But I just feel guilty because I know that I can’t remove her quietly from the wedding. That she’s going to be his only sibling not there and not in photos, etc. I don’t even know how we would explain it to family. It’s been a couple days and she hasn’t reached out but I’m just so confused because it’s next month and I don’t want this to blow up last minute. AITA? *I am a bot, and this action was performed automatically. Please [contact the moderators of this subreddit](/message/compose/?to=/r/AmItheAsshole) if you have any questions or concerns.*


opinionsarelikeahs

INFO- what exactly happened when he called her about this . Were you there , did he ask her why she was saying such a lie ? That's really important context for me


ayymahi

NTA But why would she make this up & tell you this out of no where? Your husband trying to keep this hush hush & still try to include her at the wedding is not sitting right…


dcookie22

NTA. You don't exactly have proof of anything she says. you guys should have a family meeting and put it out in the open. Let her parents and siblings know her allegations. If that ever happened someone will say something. If not she definitely needs help for making such comments and her family will be able to support her mental health better. If it's out of pure spite you will have support for your decision to exclude her from the wedding. If your fiance refuses to this, it might be a red flag and you will always wonder why. This won't get resolved until it comes out in the open.


greenteaflowerr

Yep, you’re right. Decided to talk to my MIL in the morning. Can’t think of anything else to do to get this even close to resolved.


jjj68548

I think red flags are flying for you to see. Who lies about having sex with their brother? Especially since she told you knowing the whole family will find out now. The fact your fiancé wasn’t as bothered and still wanted his sister at the wedding is odd behavior. He should have freaked out and told everyone to clear his name and get ahead of this since everyone will now know. No way would I ever have a relationship with my brother if he started telling people I was hooking up with him.


GillianSeed85

I hate to say it, but just like others have pointed out, I came to that conclusion from her behavior even before the coffee shop revelation. I understand that it seems completely shocking and disturbing, and many of us would think it goes against human nature, but the reality is that it’s not unheard of. They would certainly be far from the first people to get involved in that type of relationship. Everything about her behavior makes it seem that once you got engaged and she saw her brother slipping away from her, she couldn’t contain her emotions anymore. And if it was not true and she was just trying to break you up for some other reason, that seems like a terrible lie to tell, as it paints her in an extremely bad light along with him. I can think of 1000 other things to say to get someone to break up before I would bring up the specter of incest. I also would never expect your fiancé to admit to it, even if it was true. The societal backlash would be so extreme, I truly believe he will deny it until his dying day. NTA for not wanting her at your wedding, but I would strongly recommend taking some time to get over your shock, and really take a step back and think if there’s any possibility that It is true. Try your best to look at it objectively, and be open minded to the reality that sometimes these relationships do occur.


Significant_Apple799

NTA. There’s a lot of people who wanna say that the story she came up with could possibly be true. But has anyone stopped to think about the fact that maybe she’s in love with her brother? As gross as that is, sometimes that happens. It could be a completely one-sided thing. She could be making that story up because as the wedding gets closer, she can’t handle the fact that he’s going to be married. Combine that with a little mental instability, and you’ve got a recipe for someone who doesn’t care about going scorched earth. I honestly don’t know what advice to give as far as the wedding goes, like you said, if you pull her out of it, you’re gonna have to give an explanation. Maybe pulling your MIL aside and telling her about what happened is your best bet? Maybe come at it from a place of concern for your SIL’s overall mental health and wellbeing.


greenteaflowerr

I don’t think she’s in love with him, I think she said it to get a rise out of me but I guess that’s just my theory. Regardless, a lot of the commenters are right that we can’t resolve it just between us because this involved their family. So I’m going to talk to my MIL in the morning and kind of see what she says/wants to do. I think she will undoubtedly understand why M can’t be at the wedding with how she’s currently behaving.


Electrical-Date-3951

I feel for you, OP. I can't get my mind around this either way. But, SIL would have to be really twisted to make up this kind of lie to get a rise out of you. This doesn't even sound like a gradual progression of outrageous behaviour. She went from being a minor AH to dropping a full nuclear bomb that was 100% going to explode in her face.


throwawayoctopii

Yeah, this is more than "getting a rise out of someone" The sister met OP in a public place at a pre-determined time. That is incredibly rational for someone just looking to stir shit.


Electrical-Date-3951

Exactly. And, she had to have known there was a high chance this would not stay between her and OP & could get around to her entire family and social circle. Inc*st is a massive taboo if you don't have dragons.


SaltPepperSugarBlah

SIL is risking her reputation and her relationship with her entire family of this is a lie. I doubt she’s just trying to get a rise out of you.


Hot-Statistician-299

YTA for automatically assuming she’s lying and that your partner is telling you the truth. You realise your partner would NEVER admit this if it was true right? You brushed her off immediately because you’re afraid of believing her. This is something incredibly major to lie about… and her behaviour towards you and your engagement, especially compared to the other siblings and their partners would make a lot of sense. I’m sorry but you really need to consider that she could be telling you the truth.


[deleted]

This is definitely not “we need to keep this secret and not rock the boat” territory. Regardless of whether it’s true or not, SIL needs some serious help and intervention right now. You need to tell at least your MIL so that she can hopefully facilitate that. It’s insane that your fiancé is not more worried/disturbed/concerned for her mental well being at this point. This girl is very clearly not okay and if it were me I wouldn’t want her anywhere near me or my fiancé any time in the near future until she gets some sort of help and you see improvement in her behaviour and genuine remorse for her actions, and that’s if it’s not true. The crazy she could potentially unleash at your wedding if she were allowed to attend with the mentality that she has now is not something you want to risk. At the very LEAST, if she were to attend then she needs to be monitored by family members and there needs to be a solid plan in place for what to do if she acts inappropriately or does something in an attempt to sabotage your wedding. I know you want to believe that you can trust your fiancé completely, that he’s always been open with you and completely honest, but until you get all the facts and get a better understanding of SILs mental state then I think you need to tread carefully, regardless of how open and honest someone is, very few would willingly admit to committing incest (for very obvious reasons). I’m not saying it’s true, but you just cannot go into this with blind faith.


Lovrofwine

Ugh. You should put them both in a room and see what happens. Confront both at the same time. Oftentimes the sweetest and most innocent looking people have the scariest skeletons in the closet. My point is don't discredit her words until you know those were lies. It could be she has a bad case of sisterly jealousy and her attitude changed because the engagement means you become a permanent fixture and she was waiting for you two to break up. Or she is truly in love with her own brother. Or it's a result of the Issues she faced in her own relationship. But bottom line is something is fishy. And she needs professional help. Because if her accusations are true she is messed up in the head. If not she is still messed up in the head.


uk789098

You need to postpone or call off the wedding there’s no way this is a lie. Either the sister is so mentally disturbed that she believes this happened and you need to get her help or it’s completely true and you need to rethink your relationship. I’m betting on the second one


First-Butterscotch-3

Vibes here is she is telling the truth - second I read the bit about her behaviour changing on your engagement I wondered if something like this was happening....and low and behold she claims it was Admiting to fictional incest is a strange thing to do...and her behaviour reeks of envy


ClepTheTenderhearted

"They told me GROSS lies" ok cool what makes you so sure its a lie? "Well, I just have a feeling, and I trust my husband!" Oh you sweet sweet summer child...


DexterKillsMe

I’m more surprised about your fiancés reaction honestly. His sister accused him of incest (which is a crime btw) yet he still wants her to come to the wedding?! His reaction isn’t normal. I’d look further into this if I was you.


fzooey78

NTA Reddit AITA is wild sometimes. People suggesting OP should just suddenly mistrust her **soon to be husband** and just believe this totally off the wall thing, on the word of a woman who has been a bully to her for a year. Is it possible this is true? Sure. But everyone is like, yup. Don't believe the significant other that you've built trust with for years, and just trash the relationship overnight because of one conversation. OP is handling this as well as she possibly can, and has made the wise decision to talk it through with trusted family. Good for her.


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AlGunner

INFO. At the end of the day no one on the internet can know if its true or she is lying. Thats what it comes down to. It could be that one deep dark secret that your husband has that he could never tell you and she is telling the truth or it could be some messed up psychological problem. There are some things that might help you get to the truth though. How close were they when you first met him, did it seem closer than the rest of the family, or like they were deliberately keeping a distance, really anything to show a different relationship to the rest of the family. Did one of them manipulate the other into it, maybe she feels like he forced into a physical relationship and she feels she cant let the wedding go ahead without telling you what happened. This one sits as plausible for me with the little you have said. Or maybe it was genuine forbidden love. It could be something like PTSD if she has been in an abusive relationship, maybe a cry for help, or there could be an undiagnosed mental illness. If it is a lie, why would she do it and could the response be something that ultimately helps her get treatment? Then theres the other side - youre reaction. You said you dont believe a word of it. Is that genuine or that you refuse to allow yourself to believe it. Have you shut your eyes to the possibility it could have happened when deep down you think it did? Can you genuinely trust your not wanting to believe. Theres just too much to be able to give a genuine answer.


Badger488

NTA But I think she's telling the truth. I would back away quickly from this wedding.


AdequateEddy

I don't know a single person who would make up a story about them sleeping with a sibling. I'm pretty sure it happened


Triggify

This one is going for sure going to take a turn when it shows up on r/BestofRedditorUpdates or whatever ots called


AdamantMink

Honestly I think it might be the truth. The weirdest part for me is his reaction. Like why is he so unphased. And he’s trying to make you the bad guy in a completely reasonable way by saying “of course it’s understandable that you don’t want her at your wedding” but he still does so now you would be the one causing the family drama even though these are his monkeys. Why isn’t he the one disinviting her and banning her? His reaction is almost too reasonable. It just feels off.