Oh if I must then!
Basically, I got hurt very bad when the woman I had been seeing for over a year hurt me by going back to her husband "for the sake of the kids". It didn't occur to her (then) that it wasn't a good idea because they were rowing all the time, tho it did a few months after when she begged me to take her back because she had made a mistake again.
Anyway, when this happened, I was really hurt and wanted to hurt her in return, so I did something (not saying what) that was highly embarrassing to her.
Thing is, once I did it, I realised it didn't help me in any way, and I got annoyed that I didn't just have the dignity to walk away as I should have done. She might have hurt me, but acting like that just made me feel a whole lot worse, so I will never seek revenge again.