How do I get her to stop?

[Gabzz]

Okay so there is this girl that WILL NOT leave me and my boyfriend alone. She is OBSESSED with my boyfriend, and obsessed with ruining my reputation. Me and her were friends a few years ago, but I cannot stand her now. We stopped being friends because she was a ***** to everyone and she is crazy. So she dated my boyfriend for a week a while back. She is still obsessed with him, constantly calling, texting and messaging him. He always ignores her, and tells her to leave him alone. Then she will post on Facebook and twitter that I am a whore, that I have std's, and a bunch of other not true things that are really annoying. I attempted ignoring her, but then she started verbally attacking my family in her snarky comments, saying things about my parents, siblings and aunt who has downs syndrome and is dying. I went straight up to her and went off on her, and told her she needs to cut the crap before I get physical. If she continues, I am not afraid to get physical. She is always asking my boyfriend to have sex with her, to take her back, to leave me, and every time he says no. You think she would have gotten it by now. Then she is going to my friends saying " you know that Kyle still loves me right? He just won't admit it. He will come back" then they go at her too. Nobody likes this girl. At all. She is the most annoying human being on this planet. She won't leave me, my boyfriend, my friends or my family alone. OH and she messages my older brothers telling them that I am a whore and all this stuff, thankfully they don't believe it because they know I tell them everything. So how do I get her to back off before I loose it and get physical ?
My parents have already tried talking to hers, they don't care. They let her do whatever she wants