Yes, you're in the wrong. You act like because she cheated, it stops you from doing anything bad. No, you're still in the wrong because you still cheated. You're still in the relationship. It doesn't give you the excuse or the permission to do anything. You could have just left her and then found another person. What was the point of doing that? Because you basically just said, I cheated on her because she cheated on me. I'm basically assuming that you do not like her. That's why you cheated, right?