1. Why me...
The inevitable first question to pop up in your mind will be: Why me?! If your ex felt the need to go behind your back to be with someone else, there must be something wrong with you, right?
As I see it, sure your ego has taken a huge hit and you can come up with a thousand reasons as to why you are to blame. But trust me honey, if my ex cheated on me, chances are he needed no reason to do so.
All that self hate that follows is only the result of a broken heart and you can't really blame yourself. The point is, your relationship may have been going through the worst possible phase but even that's no excuse for your ex to do what he did.
So what do you do? Stop mulling over it. You are not at fault and he was not good enough for you. No one who cheats ever is. The sooner you accept that, the sooner you will get over it.