I've been with my boyfriend for almost 5 years, we've lived together for 4 years and we've always had a pretty good relationship, until now. We went out together last year to a party and he got really drunk, he was quite verbally abusive to me and on the way home my best friend (who is a gay guy) was helping him to walk. I've just found out that on the way back my boyfriend was groping him inappropriately and coming on to him. I don't know what to think now. He isn't particularly "manly", he never looks at porn and he's never that fussed about having sex which never bothered me before, we do have an OK sex life-about once every three or four days but if we happen to go longer without he's never particularly fussed.
Before we started going out he hadn't had a girlfriend for years. I knew him a year before we got together and he never seemed that interested, we got together because I made all the effort. I've talked to him about it and he says he's not gay and he doesn't remember doing it and he shrugged it off as just being the drink and I want to trust him but I'm really struggling to stop thinking about it. I don't know how to move past this.