Good comebacks for a horrible girl? help please? (:?

Comebacks lead to more insults and so on. It just becomes a circle. If she truly is horrible, then stop associating with her. Thinking about a comeback is just wasting your time, so is hating on someone else. While you're wasting your time thinking about her, she's probably not thinking about you. Do yourself a favor and forget about her. Move on with your life.