If you really love her as much as you say you do, you will have no choice but to look past this and move on. If she didn't do anything, you really can't be that mad. If you don't believe her and you really think she cheated on you, then your future as a couple is up to you. But if you believe her, then you will have to get back together with her, for your own sake... until the next girl comes around Luckily for me, when I fucked up my longest and deepest relationship ever, I met another great girl that I got really close with. That was the only thing that ever made me stop thinking about the last one haha.