I'm from the generation of what goes around comes around and something very similar would be happening to him on a regular basis,the guys a cunt,setting fire to your car cos some fucking slag told him too,she would have to be doing some very evil stuff for me to ever get me to do that to someones prized possession.
The saying goes to "always hit someone in their pocket" so that would be my first route,physical violence can come much much later.
You could also tell her you've got done sti/aids from some slag you were bumming behind her back,be funny to see them both down the clinic with you spreading nasty rumours about the whore all for nothing.