Two years ago I met a guy at work and found out that he was married but he told me that things were not working out of course. Well I had just came out of a really abusive relationship and needed to get over my ex quick because I kept going back to him because I did not want to be lonely. To make a long story short I hooked up with this married man without any intentions to keep this fling going and we kept seeing each other even though his wife found out. He told me that he loved me during our affair but I went on and found myself a legit boyfriend and tried to move on because I knew his wife would always deal with his cheating but would still call me when she cannot find him. Well while with my new boyfriend the married mans wife called me and my boyfriend answers my phone and she told him that I was still messing with him and we ended up breaking up. I was angry and started to mess with the married man again and of course she found out and packed his things. He moved out and came to live with me and she had no idea he would but he said that he just loved me too much to stop what we had going on and that he wanted to be with me. He said he did not love her because if he loved her he would not of cheated on her. Anyway we now have the tiest relationship ever because she wants him back and he refuses to go back. She is always trying to kiss him when he goes to pick up his kids and tells him that he needs to come home. She won't get over him and it has already been five months since he left. She texts him late at night and I am constantly fighting with her and I really feel like kicking her but I know its not the right thing to do. I'm to the point were I just don't want to deal with it anymore and accept the fact that I messed up by messing with a married man in the first place. He tells me everyday that he loves me and that he'll never go back but there is just no trust and if I cants trust him then what is the point of fighting over him. I basically need the opinion of others to make sure I am not the only one who feels like I should bail out on this relationship. I know he'll go back to her anyway

Why do you feel you can't trust him?
It sounds to me like he more than likely doesn't want to be with her. Sounds like she was probably controlling and that for one is a turn off to most guys.
She did things in for herself by telling your boyfriend that you were still seeing her husband.

Ok first thing to look at if he cheated on his wife that he once loved what could happen with you? I can see how it could ruin your everyday life because your constantly thinking about that when you think of him (I would be) So if you think and worry about it and have to constantly second guess your relationship it's not healthy and it's just not the way to live your life. The thing with the other boyfriend just kind of seems like karma. But if you feel like this man is the one and you can make a life in the future and you could learn to trust him and so on then I guess go for it but if you always doubt it will eventually end.