Please don't judge me, please help!
Most Helpful Guy
I'm not judging you, but are you sure that's really what you want to do? Wouldn't you just be proving his point, especially if it could be tied back to you? Hard to defend against that.
Nevertheless, I'm not above a good revenge, and I've done my share in my day. If he has a car that you have some access to, water in the gas tank won't wreck the engine, but it'll complicate his life with quite a few unexplained stalls and some fuel treatments. You could take to the next level, like I did once, and just take the whole gas tank. I wouldn't recommend that, though - it could be considered felony theft.
A more benign revenge (and one that won't get you arrested) would be to show him how happy you are without him. Be seen having a lot of fun with friends, flirting, and just in general having a good time. Trust me, word will get back to him.
Whatever course you end up taking, please do be careful. Revenge is justified sometimes, but I'd hate to see you get in trouble over it.
Most Helpful Girl
Tell everyone he is bad in bed and fuck someone close to him real close