No, I don't really think that it would be right. If he cheated on you that doesn't give you the right to cheat on him, haha and if you are thinking about screwing another dude while you are in a relationship then why are you guys still dating?
Would it be okay cheating on a boyfriend who cheated before on you?
"Two wrongs don't make a right"..but, hey sometimes, if a girl feels it's right to, "Get him back" then, go for it! Why? Because, not only will it make you feel good to be with someone new who may appreciate you, but go ahead and let your bf find out! And then dump him! Or, you can always just break up with him and walk away(make sure to not say nothing but, "Its over") I bet he will feel bad, and may find way back to you!! Just remember to "Let the DOG chase you".