not sure what to do

so my boyfriend has a "best friend" that's a girl. not much of a best friend cuz she's selfish and is never there for him. anyways...I didn't have a problem with her at first. we have been together for a year btw. she started posting pictures of my boyfriend on Instagram and Facebook I told him I didn't like that and he told her to stop.  she kept doing it. he told her 4 times to stop. he finally got fed up and deleted and blocked her on Facebook and instagram. I told him I don't want that to come back and bite me in the ass cuz I never asked him or told him to do that. I'm tired of her drama and bullshit. she's a drug addict and is not in rehab. she uses him and I'm tired of it. she always calls him and texts him. I get that they are friends. that's not what bothers me. the fact that she has no bounderies or respect for me and my relationship with him. it has caused a lot of drama and unnecessary arguing in my relationship. any advice? help!