Have you ever dated someone just to get back at an ex? Or did your ex date someone to get back at you? Maybe a friend, or their friend, or a family member of theirs? I haven't done anything like this myself, and I doubt I ever would. I think it'd be wrong for the person you're using, considering they could fall for you in the process.
I have been in my share of bad relationships, some that resulted in my exes trying to get back at me, but thankfully it wasn't too bad. I did end up in breakups I didn't like, and they still put it in my face, but I usually did my best to just move on and leave the past behind. But sometimes you know when someone is trying to throw it in your face. I saw my ex a few times after we broke up, and everytime I would see her, she would be mackin on some dude and looking right at me. I just walk away. Hopefully it was worth it to her, because I imagine the dude she was doing it to, was probably falling for her.