(Poll for Ladies) What should i do to keep this tramp away from my man?!?

Hi Im Shey. My bf''s ex was always still in our picture and i was ok with that. But suddenly shes been acting ual around him.And everytime I ask her to stop she says ''Im just playin''', but days after it continues. I really want her to stop but I dont want to get violent or get anyone hurt. I dont have a problem with her being his friend but she is acting like a . How can i tell her to back off nicely without being rude? Or If you have any other ideas please share them!