My boyfriend had a incestuous relationship

I started dating this guy quite recently. I'm a bit new in this relationship stuff but things had been going well so far. However, about two weeks ago we were talking about secrets and he said he had a terrible one he could tell no one. Naturally I got curious and started a guess game. In the end, he didn't tell me what it was. I became a bit paranoid after that as he was serious about it. I thought he had comitted a crime of some sort, and that idea terrified me.
So this weekend I pressed him to talk. At some point, I was feeling a bit bad 'cause I knew I was walking on thin ice but I couldn't stop. Then he revealed that it was something sexual and technically not a crime. I thought he maybe had a strange fetish but he said no, it wasn't that and then asked me "please stop trying to guess".
I stopped and we entered a cab to go back to my place. Then it hit me. I knew what it was and the worst part was that there had been signs for some time now.
To put things in context, he's lived basically his whole life away from his dad part of the family and been around for only 2-3 years. My best friend (his cousin) told me that she saw their aunt try and kiss him once while she was a bit drunk but he refused her back then. But I know the woman and she is very affectionate to him and seems always in need of attention. I mean, she's nice and funny in general, but there was something a little off about their relationship. Almost intimate.
When we got home, I was crying. I was a little guilty for pressing him, a little disgusted by my own thoughts. When I finally told him what was on my mind, he gave up and said I was right. The thing is, it supposedly happened only a couple of times. But I don't know how to act. I still like him but the whole thing makes me feel nauseated, I can't stop picturing him with her. He says he doesn't regret it exactly, he's mostly afraid of the consequences if the rest of the family finds out. How should I feel about this? He tells me they never did it anymore, it's been over a year since they did for the last time and that now he thinks of her as mother and helps her with her current romantic affairs, as nothing really matters anymore. But he sleeps sometimes at her place when in town when he can't stay at mine. Should I feel jealous? Am I getting into something really screwed up and the best option is to back out now? I really do like him and the fact that he was honest with me does count too. But I feel insecure, I feel wrong. I don't know what to think about both of them. Who am I to judge? Things happen. But could they happen again? Even something as uncommon as this?

Just some questions if that's ok, so I understand this better.

He had sex with his aunt "a couple of times." How old is he? Was this recent or like during teenage years??

And sorry for the next question but was protection used? Bec if you plan to have a physical relationship with him it would be nice to know.

I'm also not sure why someone would say they had a terrible secret to someone unless they wanted to get this secret off their chest.
What do you wanto do with this information? Has he given you any background information about it?

No, it wasn't in his teens, it happened not too long ago, I guess he was around 21-22.
I'm not completely sure if they used protection. He told me he was wasted the first time and remembers very little of it, he basically woke up on top of her and was feeling very sick (from tre booze not the situation). I believe she was quite sober and aware though.
At the second time, he was actually conscious but he was nervous and had some trouble with keeping the erection. Not sure if a condom had anything to do with it anyway.
Well, you do have a point. He did say to me that he wanted to tell but didn't really, 'cause now I hold an information that could ruin his family. He thinks I might tell my friend who is also his cousin in case we break up or something. I don't see myself telling his secret to this cousin even if I was mad at him, but I understand why he can't completely trust me at this point. He said I shouldn't have pressed him because he just can't lie.

I'm not sure what I should do with it. I don't wanna end things for something that happened in his past, but I don't know how to act from now on. This is disturbing me much more than I let him know it was. It's just that there's been a tension between them from the start, I simply chose to shrug it off as I didn't think responsible adults like themselves would do such a thing.
So now I feel weird knowing he slept with his aunt. Maybe this will pass and I'll be able to look at them and not think of it. I just highly doubt it right now.

This is a really tricky question.

On his side, I've seen questions similar to yours when the couple could never stop, where the relationship doesn't end. But then again, there are questions when they do end it entirely and at least one of the couple, let's say your boyfriend, spends the rest of his life feeling guilty about it.
Before we transition to your side, I do need to point out that this was a secret he had been harboring and something he does feel guilty about...but he told you. So he trusts you enough to tell something he has never told anyone and trusts you will never tell.

Now, your side. It's normal to feel confused, but you did pressure him into telling you something he wasn't comfortable enough to tell anyone. So here is what you have to decide: Can you live with this information? Can you live with breaking up with him because of something you had forced him to tell you? Are you going to be holding this over his head during family dinners or arguments with him? Would you tell someone or are you sworn to secrecy?

Personally, if I was in your position, I'd be just as confused. I would be doing the same thing you are doing and be asking what the best move should be. But the questions above are questions I would be asking: can I live with someone who had a romantic relationship with a relative, would this relationship continue, and would I want to still be in this relationship? Only you can answer that.

I can only guess at how confused you must feel about what you have discovered, Patagonia has raised some of the many questions which I'm sure are already spinning around in your head. But although I can understand that you probably feel like you need more information, I can also understand that this guy would probably prefer not to discuss intimate details of his incestuous indiscretion. If fact most people would not want to discuss their previous relationships and would be annoyed if their new partner insisted on knowing every detail.

So I guess what you should do is make your decision on whether to continue with your relationship on things like has he given you any reason to believe that you can not trust him ? To the best of your knowledge is he honest with you ? And can you get over your jealousy or is it something that is always going to be a sticking point for you ?

Finally just one more thing..... I have heard about such intimate relationships happening with family members that have been estranged until adulthood. I believe the reason supposedly behind it is that when family members come back together there can be strong loving feelings and almost an instant chemistry but it can be hard to rationalize these feelings and they are misinterpreted as sexual chemistry. Might be worth doing a little research it may give you the answers you desire

Good luck

Yes, I think those are the questions I should be asking myself. As to the answers, they're mostly inconclusive I'm afraid. Maybe I discovered the whole thing too soon. I guess I can cope with the facts and stay with him if I really want to, but I don't think I'll ever be 100% sure about them. I believe him when he tells me it's in the past and they moved on. In the other hand, what if we fight or if she asks him for just one more time when she's feeling particularly lonely and then it starts again? The second time is never as hard as the first. Cheating is bad anyway, but that kind of cheating is just cruel.

I think I can keep this to myself, even if it hurts. I can even act normal as nothing was ever told. I'm not holding this against him 'cause what would be the point? Also, I'm gonna keep treating her as I always did. Really, it's a strange situation but I can pretend everything is just as it was. I wish I could simply be sure he wouldn't do it again, at least not while he's with me.

Actually, we've been very honest in our relationship from the start. It has probably something to do with the way we began dating. He says all kinds of stuff to me and is not afraid of sharing details about his past relationships, even more intimate details. And I guess that's why he started to tell basically everything after I found out. Like, he doesn't really seem ashamed or guilty about the act per si. He's just afraid the family knows. He said they decided to stop after the second time because it wouldn't work very well considering everything.

I find this last bit you said very interesting and might explain why this happened. I just hope it's something that gets weaker or less confusing over the years and that he doesn't feel tempted to do it again. I think I wouldn't be able to take it.

I think that once like your partner, the estranged family members have gone down the intimate route in most cases they realize they were mistaken.