I feel for you, Zoso. I had the same problem with my BPD ex-friend, and she did not hesitate to get others involved (her mother, our mutual friends, etc). I cut contact with anyone who didn't understand that the way she treated me was abusive, and anyone who believed her ******** wasn't woth having in my life anyway. There were a few people who saw through her facade for the bully she was, and they are still in my life today. It took a few months for her to stop harassing me, but once she realized I wasn't going to feed into her drama, it did stop. Here's a perfect illustration of her manipulation; about 6 months after going no contact, by pure chance she found out through an old high school friend of ours that I had just broken up with my boyfriend. She immediately sent me a text about how she missed me. No apology for her behavior (and it was bad), I remember laughing because after distance and therapy, her manipulation tactics were just so transparent. I deleted the text, and haven't heard from her since.
Stay strong, it may get way worse before it gets better, especially once she realizes she no longer has a hold over you (that whole black and white thinking). One of the books about BPD I read was called I Love You, I Hate You, Don't Leave Me. Man, does that sum it up. Now that she realizes you're really leaving, she is probably panicking and will go to desperate measures to get your attention, even if it's negative attention. I am glad you are able to see it for what it is and respond in a healthy manner. Keep it up, the view from the other side is amazing. It feels so nice to not walk on eggshells all the time, I can finally BREATHE. I hope you feel that way soon.