Ex-boyfriend and his new girlfriend keep harassing me?

My ex and I mutually broke up over a year ago because I just wasn't into him anymore and I thought he felt the same way. I added him on facebook a month ago just because I thought we both didn't care anymore. Turns out he does. He wrote a very mean message to me claiming that I am still obsessed with him and constantly talk trash about him to everyone I meet. This isn't true, in fact, I haven't thought about him or spoken of him in months. After he wrote said message he blocked me. Now his ex gf (who is 15 and me and him are both 19) tried to stir up drama between me and my best friend over facebook saying that she doesn't really like me and all this BS. I asked her what she was trying to say and she said something along the lines of "You have no friends, but you know that, you live it everyday". It was true that while i was with my ex I was very depressed and didn't think people liked me, but I am so confident now and a completely different person. I just think its so low that she'd bring up something that I told my ex a long time ago. But I don't care, I'm over him and don't want anything to do with either of them. I already blocked her, but she toiled papered my best friends house. How can I make her just go away and far away.