Your ex GF ain't doing s h i t. You're doing that to yourself.
The jealousy is the only thing you can hope to control. She is doing what she is doing, can't change that. You have to take a deep breath, wish her the very best and move on with your life, sorry.
Play hard to get. Walk away and see if she follows
Wish her well, move on... and fine someone new.
It doesn't matter if she is. Live your own life and focus only on what's relevant to it.