My mom also has BPD (and is a drug addict). I went NC with her for several years. I am actually back on limited contact with her. I will talk to her on the phone, but I don't put up with BS.
It is really important to have boundaries with people with BPD. They will keep testing your boundaries, so you have to stick with them. It got to the point where I would no longer respond to mean emails and I would not call her back if she left nasty voice mails. I also started hanging up on her when she got mean. She has actually improved a bit over the last couple of years. I think she got the message.
Another thing people with BPD do is splitting. They will say things/do things to set one person against another. It sounds like she is doing that with you and your siblings. I wouldn't trust her when she says that your siblings said this or said that. She is creating drama so that she can be in control.
Also, people with BPD see things in black and white. So right now, she may see you as the "bad one." Other siblings may be the "good ones." She may switch the roles at other times. Don't take it personally!!! It took me years to realize that it was my mom's mental illness talking, and it was nothing that I had done.
If you have not done so already, I suggest you read the book, Understanding the Borderline Mother: Helping Her Children Transcend the Intense, Unpredictable, and Volatile Relationship.