I cant get over it

Ok so a few months ago my bf cheated on me and the details of it are so dirty and horrendous. He asked for forgiveness and we slowly started talking again. But ever since he cheated it seems like he's way less romantic and all he ever thinks about is "fucking", every time we get intimate I can't stop thinking about what he did just because he seems so non emotional. I just Can't get over it! I can't get over he fact that he cheated and had sex with someone else. WE WERE EACH OTHERS FIRST TIME. I think that has something to do with it. Someone help me. I'm losing it! Thanks.