Sometimes when a person cheats, they do regret it because it hurt you and your relationship. However, even though they regret it and hate themselves for cheating and hurting you, they sometimes still may not want to be with you although they are sorry. My advice is to just ask her what she wants. If she says she don't want to be with you anymore, then forget about her. But you can't stay with her, fight after fight, and not do something about it. You need to follow your own happiness, and do what is right for you.