I hate his ex and she keeps talking to him?

okay so my boyfriend broke up with me in april and a week later he had a new girl, who he went out with for a week, and then he got back with me. so she keeps adding him on facebook and she even told him that she didnt wanna talk to him cause he got back with me. and outta no where she called him telling him shes in an abusive relationship. i think it was a lie, cause shes a freshman, and probably immature. and they are not even close so whyd she tell him instead of close friends.? she probably wanted attention from him. and why would she call him when they arent even close and he didnt even talk to her anymore. and then the other day she sent him a message on facebook and was like "i <3 how you always delete me.. JERK.(:". shes so immature, he likes me and im his age, im gonna be a senior and hes going to college. we have been together for a year and a half. i want her out of my life. what do i do.? whats wrong with this girl.? does she still like him.?