When people mistreat you, let them go!
You wouldn't let someone who was abusive to you stay in your home, so why would you let them take up space in your sacred temple?
Don't linger on their social media page, don't drive by their house and don't worry about what they think of you. Chances are, they aren't thinking of you at all and you should return the favor.
Call in your Angels to bind obsessive thoughts so that you can go about your day and when you are ready, you can heal them once and for all.
You deserve the best! If you were mistreated, then that person was not the "best" for you. Let go and fly!