Although there's plenty of funny in this thread, the only practical advice I've seen is in #29. You're asking about your relationship with your girlfriend and that's the issue closest to you.

It's fun to think about revenge and all that, or just embarrassing the guy, but if I were you I would want to focus as soberly as possible on what's going to bring you the most satisfaction? You could humiliate the wrongdoer, his daughter, maybe their whole family. Or if the "socratic approach" works, and you keep with it, someone doing something really bad, from a bad attitude, could change.

Is that likely? I don't know. I've seen it happen, and sometimes it's hard or actually lots easier than you think. Depends on your situation and what it's worth to you.