What is the best revenge against your ex who emotionally destroyed you?
To help you conserve your time and energy, I'm going to tell you something that you won't want to hear. You may want to prepare yourself for this:
There is no revenge you can exact against an ex who emotionally destroyed you.
None that's legally condoned, that is. Simply because your ex doesn't care. If this person is as compassion-impaired as you paint them, any attempt at revenge will be perceived by your ex as a pesky "issue" that refuses to go away. You will seem like a circling gnat. A human gnat. Your ex might get annoyed or even pissed off. Most likely, they will see your attempt at revenge as humorous, or pathetic. But nothing you can do will strike at their heart and hurt them the way they hurt you-ever.
Look, I understand your pain and your need for retribution. Some people tilt more bad than they lean good, and when they get away with hurting others, it feels criminal. If life were cosmically fair, people who hurt others would automatically be served a healthy dose of their own bitter medicine. But the unfortunate fact is that this world is far from fair, and a lot of people are shitty. Case and point, the ex who emotionally damaged you just because they could.
Here is what I believe, though: I truly believe that if your ex is a serial a$$hole who behaves like this to all romantic partners, s/he will eventually go up against someone stronger and far more cunning, and that person will take them down. It will not be pretty. It might not be next month or even next year. But just wait and see what shakes out ...
The reason I write this is that I've seen what others call "karma in action" far too many times to disbelieve it.