I need help.

I had a best friend all throughout high school. We were very very close and she was my one true friend. Junior year things got rough, I heard that she was telling other girls in our grade that I didnt like them and that I was always talking badly about them.

She was just making things up about me to other people and when I confronted her she said everyone was making it up. Multiple people were telling me these things she was saying so we stopped speaking to each other for 7 months. I missed her very much and wanted our friendship back so I forgave her and she forgave me for not talking to her for months and we were back to being best friends.

Freshman year of college , it started up again, she was telling people bad things about me, she would tell all of my secrets to other people..people I barely knew, she would ignore my phone calls and never want to hang out. She accused me of trying to hook up with her boyfriend and told me I ruined college for her.
(I would never ever hook up or even touch her boyfriend)

She told our other friends that I was a bad best friend and so on. So I just stopped making an effort to talk to her and we stopped talking. Then it turned into a big fight and I deleted her off facebook because I couldnt handle reading all of her statuses and posts to other friends about me. That was a bad decision because she got so many people involved with the drama. She told everyone she talked to about how horrible I was and how she didnt do anything to deserve to be deleted off facebook and she told all of my deepest secrets.

She would tell people not to hang out with me and try to make them not like me. I havent spoken to her in almost a year and she still talks about me. Today, one of my friends was telling me the things she was saying about me. She even convinced my boyfriend that I was a bad person and he refuses to talk to me.

I dont know what to do about this. I thought she would stop after sometime but its been almost a year and she still makes things up about me. We dont live in the same city and I dont have a facebook anymore, yet she still talks badly about me every chance she gets.

The only reason why it bothers me is because she is actually convincing some people that Im a bad person. I really really like my ex boyfriend. We havent spoken in a month but it upsets me so much that she would stoop so low and take him away. Now my ex and her are really good friend and its so upsetting. She tries to make anyone Im close with better friends with her. I dont know what to do . Please help !!