I don't get my ex, what should I do?!?!?!?

I think you should decide what you really want. If choose one, you might hurt the other, but try to make make the best decision for you. Your ex did a mistake, not a huge one though. From my personal experience i know that it's hard to forget when your boyfriend has cheated on you, but my occasion is totally different, believe me. Since he's really regretted it and you say he's not a "player", that shouldn't be a problem. The only thing you should think about is who of the two you really want. And stick to that one. Good luck! :)