Very well put Magic Aura! I agree that you should take a break. Try meditation. This will help you clear your mind. Search instructions in Youtube if you don't know how.
Practicing LOA in your current state of mind will only lead you to a more miserable state. And even if you practiced it the day after you broke up, it wouldn't work, unless you are both in the same frequency of thought. LoA cannot manipulate free will.
You do not want to be with someone that already cheated on you. Chances are that she would do it again. You deserve someone better. Take a break then think of your situation again. Maybe perhaps you only want someone like her. If that is the case then focus on the aspects that you want on a girl. If you do it right then you will meet someone like that eventually.
What do you mean the same frequency of thought?
Simple, your ex should also want you back or someone with the same aspects/characteristics as you. Then if you both are thinking the same way, then the universe will make a way for both of you to be together again.