Hey Kim -- I read your story and it reminded me of something I went through recently.
Not to make it too long of a story, but after my separation/divorce I became friends with another divorced woman. In the beginning, she was helping me out, helping me to deal with my emotions following the divorce, helping me get settled in my new house, etc. It was all good. Until it went bad....
I soon realized she had some sort of aggressive narcicisstic personality disorder. She was manic and started calling me about 20 times per day. She wouldn't leave me alone. Then she started fights with me. She didn't agree with some of my parenting decisions (I never asked her opinion) and started challenging me all the time. We got in a huge fight once and that was it. But then we had to make up and be friends the next September since our kids were in the same pre-school class. I gave her another shot a friendship, and then the same thing happened all over again. I made a comment on facebook that she didn't agree with, so she flipped out and told me I was a "f*cked up girl" and that I needed help.
I have determined from this that there are people out there who are toxic to us, people who are unbalanced who like to blame others for all their problems, even go so far as to be aggressive and mean and try to make you feel bad about yourself. It sounds like this former friend of yours is the same type of person.
I have cut off ties with this former friend and fortunately for me, she has stayed away. I can only recommend that you try to do the same, document everything she does and keep your cool (which it sounds like you are doing).
It's hard to believe this kind of stuff happens to use when we are adults, but it does. I hope it helps to know that you're not the only one who this has happened to. Hang in there!
Laura