How long have you and your boyfriend been together? I know...it hurts when someone cheats on you...
Don't cry over him, he's not worth it. If he wants to be with someone else, then let him. I bet there's someone else out there, way better than him :)
I don't know if I can cure heartbreak with words, but if you get your friends to help you, it would be so much better :)
Remember, everyone goes through this at least once in their life. Maybe you can find someone who had the same problem once...
If you really can't forget about your ex, maybe you can fix your eye on someone else. Maybe another guy? Believe me, your ex will be SO jealous when he sees you laughing with another boy.
Put your eye on a certain goal, and don't ever look back... because once a cheater, always a cheater :)
Remember, you're BEAUTIFUL, and that idiot is stupid if he thinks that cheating on you was okay.
Have a great day! :)