What are some legal and discrete ways to get back at a cheating ex?

Hello everyone, I'm writing this from a burner account because my ex probably knows my other accounts.

We ended things a little over two months ago, but my friends decided that I was fully healed enough to FINALLY reveal he had been cheating on me for the past year and a half. Now, I knew he had been cheating on me with AI (he said it understood him better than anyone else) but APPARENTLY he was on dating apps for a long, long time. I want to find a way to inconvenience him that isn't easy to trace back to me.

This man for the record does not care about anyone other than himself, so the notion of "just move on" or "be happy" will come in a week or two when I've officially closed this chapter of my life out. I'd prefer something simple or not super long-term since honestly I will not care by this time next week to continue this plot.

How do I know he'll never try to come back to me or regret cheating? He already has a new girlfriend, and she is completely unrelated to this issue between the two of us. However, I tried to let her know through a friend of hers what he did and she got mad and accused me of trying to "sabotage their relationship" because he's "too sweet to do something like that."

lol she's on her own now honestly. good luck babe

anyways guys, does anyone have advice on what I should do to inconvenience him?