Two years ago, I had a girlfriend cheat on me for no reason other than she is a whore. I broke up with her on the spot, and she tried to act like I was in the wrong. Later, when she realized that we were over for good, she tried to rub it in that she cheated on me ("well fine I'll go F*ck him again!).

I sent an anonymous email to her school about her extracurricular activities, and she got expelled. Haven't given her the time of day since.