I'll try to make this as short as possible. I was with the same girl for almost 3 years and we did it all, bought a house together, spent every day together, talked about marriage, ect. Well, her ex b/f came to visit for a few weeks because he's in the military. I had my suspicions because I found some email written between them but she swore they were nothing but friends, and I trusted her for some reason. Well, while he was in town, she started acting really strange, hanging out with 'friends from work' (him), but I had no proof of anything happening. He then left to go back to the military base, and she went back to being her normal self. Then... the topic of marriage came up again and she was very persistent on wanting to get married. I thought she was being sincere, and we even told my family about our future plans. The VERY NEXT DAY, she was talking to the ex online, and I went back and read everything that was said, and that's when it hit me. She had slept with him and was with him every night she wasn't with me. I even talked to him online, and it turned out that she told him that she was single. So she lied to us both and figured that neither of us would find out about the other. I was hurt, sad, but mostly angry that she'd pull something like this. I got all my stuff out of her apartment, and decided it would be best to cut all ties with her. Well, it didn't last long, after about a week, we were talking again, and then hanging out again. But I couldn't even walk into her bedroom knowing what happened in there. I was trying my hardest to forgive her, but I'm really starting to think that it's impossible. Tonight is what pushed me to write this and ask for advice. I got out of class, and called her phone because she wanted to hang out. Well, she told me her 'friend' was over and that she would call me later. So I went over to her apartment anyway and sure enough, it was a guy she works with that calls her all the time. I knocked on the door, she got pissed, let me inside, and he got up and left because I made him feel uncomfortable. Well, I left shortly after because she was pissed off, and instead of driving home, I sat in the parking lot and waited about 20 minutes, and sure enough, her 'friend' came driving back into the parking lot and went into her apartment. I called her, told her I wasn't going to let her do this shit to me again, and said to never call or write me again, because she fucked up again, and I don't need someone like her in my life. I just don't know what to think. Part of me will always love her, especially after 3 years. But I can't keep putting myself through this day after day. I wish it was easy to forgive and gain that trust back, but so far it's only gotten worse. Anybody have any advice on what to do in this situation? Anybody ever tried to work things out with a s.o. after they betrayed your trust and cheated on you?