Most Helpful Guy
Put him in your rear view mirror and look towards the future to more positive things. Revenge never solves anything.
Most Helpful Girl
Don't do anything harsh to get him back. Be the better person and break up with him, that is the best way you can get him back. Now that was my good conscience talking. Now to the bad one, if you really want to get him back, you can key his car. If he doesn't know that you know that he cheated on you, you can always play the game pretending that he is innocent and then humiliate him in front of a bunch of decent people and start crying a little so everyone would look at him like a total jerk. Put Nair in his hair, that one is really cruel, only do this one if you really feel cruel and extremely betrayed. Or you can wait a couple days or weeks (only if he doesn't know that you know that he heated on you) and follow him on his days off work and try to snap some juicy pictures of him cheating on you then purchase a billboard ( they're expensive but if you have access to some of his money, use his to purchase it) and post a no explicit picture of him cheating on you. if you do this one, you will look completely insane. You can bust on of his tires. Don't mess with his food and don't injure him. Remember you can get used for stuff like that. But the best thing you could possibly do is show that you're happy without him.