Nothing is gained by being an asshole to an asshole. All you've done is provided him with documentable proof for how terrible and vindictive he thinks you are. It doesn't matter if every other claim he's made about you was a lie.
The best move is to avoid playing the game.
I think the person in question would be in vastly larger amounts of trouble for even raising his head above the cesspool he floated in for a moment. It would be like a chase from the Benny Hill show with local housing enforcement, HMRC, the police and a trail of angry and abused tenants.
The best move is making the game worthless so there are no winners. Shit on the board. It's a stalemate then.
The put the keys through the letterbox thing was actually a masterpiece of idiocy on his part which I refrained from mentioning to him.
Isn't every long-term benefit long-term only in hindsight?