What would you think about me getting my ex fired?
Why do you want to get him fired?
Because fuck him that's why.
Your anger is understandable, but trying to fuck with your ex's life isn't a road you should go down. Just move on with your life.
If I don't try to fuck with him, who will?
The thing is, you should move on rather than trying to get even. Try to stop thinking about him at all rather than worrying whether someone will fuck with him.