Found out this guy I date has a girlfriend, do I expose him?

[Serpiente]

this guy from college hit on me in the library before christmas and we went out 2 times before the new year, nothing happend.But something didnt feel right so i told him to back of. 2 weeks ago we found out we had mutual friends and we both was invited to a dinner with them. Nobody knew we dated and still dont. We talked at the dinner and we both had a good time with our friends. So when we left, me and him had to go the same way and wait for the train. Suddenly I ask him if he has a girlfriend because I got a feeling, and he made sure that he has not. But he still lives with her ex (from a 3 years long relashionship) because of the apartment contract and they still share everything (like bed but not have sex) and none of them afford to pay the rent without each other.I was really sceptical and I asked and asked and told him to be honest (in a cool and nice way so that he would confess) because I really would not judge if he did. But I thought its better for both if he confess before anything happens. Again he swore and made sure that nothing was on and he was gonna move soon anyway to get closer to the college. He also said he couldnt take me home because she would probably go crazy (he talked about her like if she was a crazy/annoying/stalker/witch). So i believed him and later when the train came we kissed. 2 days later we met again and went to the movies and a pub later that evening and had a 2-3 of beers/wine each. Then again we kissed a lot and had a really great time, so we agreed to meet again on the 1 coming friday. Now for a couple of hours ago I could not sleep (its 4 am now) and I randomly checked his facebook for the first time because i dont use facebook so much. I found out that his stillgoing girlfriend has written on his wall and confirm that they had 3 years anniversery at the exact same time he hit on me back in the library. So I cheched her facebook and instagram and they have LOTS of recent (as in from 2014) pictures and posts together. So now that they're still together, I texted him about that and got upsetbecause I dont wanna get in between first of all. I definetly dont want to be THE REASON they break up. But still I cant help to want expose him to his girlfriend. Im not sure because i have never faced this kind of situation. (Im 21 and he is 24.) His girlfriend seems really sweet and I feel so bad for her. But I really dont know what to do because I litteraly ASKED HIM and made sure that i would not get mad even if he has a girlfriend and I gave him several chances to explain and to confess. I thought it was odd that he couldnt take me home, the meetings were secret for some reason, and he came up with bad answers and things didnt really match up. But still, he insured me like 100% and told me that he didnt have a gf and otherwise that would show up in facebook after 3 years long relashionship. So I believed him and I cant believe that I took his word for it because when I get a bad feeling about something, its always a good reason. And I always know when people lie to me. The question is what shoould I do? I found her number from the yellowpages (Norway) and I called her with hidden number and she answered. THIS IS THE FIRST TIME SOMEONE ANSWER ME WHEN I CALL WITH HIDDEN NUMBER, and especially at this kind of time at night. I feel so bad, and I kind of really want to expose him to her because I now somehow know that this definetly cannot be the first time if he could fool me. Nobody has ever fooled me. Do I tell her or do I move on with my life? I really hate him now and even though I dont have any feelings or anything for him, i still get mad when thinking about him and knowing this.

To me from the pictures and the post Ive seen, it seems like that she is SOOOO in love with him because in his facebook there are no pictures, except from posts that she has posted on his wall. That's why I want to break this of because this poor girl is cheated on and Im the one cheathed with her boyfriend.

so please, give me an answer or 10 !! I would be more than thankful.

[RWgirl]

I'd personally not talk to the girlfriend. It'll probably succeed in causing a fight but little more. You know how there are warning signs something was really wrong that are totally clear now, but you didn't realize what they meant back then? She's seeing warning signs he's cheating, I can guarantee you. Nobody is as smooth as they think they are.

Also, you know how he lied about her and said she was crazy, stalkerish and generally horrible? He can say the same about you, "I don't know what that girl is talking about, I met her with some friends, we chatted, that's all. I mean, we didn't even hang out one on one, but she started acting like we were dating. I even said I had a girlfriend I live with!" or something like that. I've known women who have been with cheating men, have gotten photos emailed to them, and the guy has been able to talk his way out of it.

Finally, it sounds like a huge motivation for telling her is that you're angry at him for tricking you. It's totally normal to feel that way, and we've all felt that before. He's a horrible person and that was a rotten thing he did to you. However, that's telling her out of a desire for revenge, so think long and hard about if this is really going to be what's best for you. Revenge has a nasty habit of having unintended consequences, and never quite works out the way it's planned.

Chances are, she knows something is up and she's in denial. She'll accept the fact when she wants to. Maybe (and that's a big maybe) this will hasten the end, but most likely not. Beyond that, you can't really know what goes on inside the relationship. Facebook posts can be tailored to give a certain perception, they aren't necessarily a reflection of real life.