What is the most savage revenge you've seen someone take on their ex?

Well, I don’t get around much, but I have an amusing story (not very savage, I’m afraid).

I had a friend in college who routinely stepped out on her boyfriend. Not only that, but she told me that she got busted by him every time.

He was remarkably patient with her, but finally they had had enough of each other, and he moved out.

Shortly after they split up, she came over to his house with a bottle of wine and found him in bed with another woman.

She was so mad, she broke the bottle of wine on his car windshield as she left.

This was after they broke up. After months of her cheating on him.

I imagine he thought it was well worth the broken windshield to get her karma back at her.