I did a cruel april fools to my ex
Oh my, why would you do that?
I want to screw up his new relationship as much as possible, he can't be so happy!
Your ex is your ex for a reason. Leave that relationship in the past and stop meddling in his life.
It's not like I'm destroying his life. A jerk will be a jerk no matter what.
You only are fanning the flames of your hate about what happened. You need to move on and if you can't let it go talking to a therapist might help you sort your feelings.