He cheated when we first started dating.... that was over 2 years ago?

My boyfriend and I started dating almost 3 years ago. We deployed together a few months later and he got to come home for vacation before I did. He came home at the beginning of the deployment and I got to come back near the end of the tour. I even drove to see his family, wthout him there on R&R. After we got back, we got to go on block leave, and I went home with him to see his family, instead of mine. I just recently got out of the army and we bought a house in his hometown. He doesnt have any kids, but I have two. I just found out he had cheated on me while he was on R&R, with a girl who is a real close family friend. He swears it only happened those two weeks and he was drunk the whole time. And he swears it was the worst mistake of his life. Now I realize that cheating is caused by both parties most of the time, but I didd't do anything to provoke it. We hadn't even been together a year yet. NOw I'm sitting in his town, with his friends, cause he's still in the military, and all I can think about is if he's cheating on me again. I have to see this girls family, and I have to be nice to everyone one, but all I want to do is cry. She knew we were together. I don't know. I can't talk to any of these people about it, cause they'll take his side. They're all HIS friends. I don't know anyone here... And I can't talk to my family about it, because if we ever do get married, they'll never like him. But it's ruining my life. And I can't get him to talk about it. He says there is really nothing to talk about, he's told me all there is to know. I feel stupid for even moving here, and wish I had a way to move out.....