Help, my friend stopped speaking to me over NOTHING?

i had a fall out with an ex "best friend" recently, she basically started treating me in such an awful, resentful, hateful, passive aggressive way that i had to get her off my back, even though she seemed to want to remain friends, i pushed her away. the problem was: I think she is extremely envious of me. She had an eating disorder which I just found out about after we broke our friendship. I found out she used to have anorexia. However, now she is pretty ...for lack of a better word, fat, chubby, and I am skinny and a zero size, basically. After she started acting really hateful towards me for a simple reason (I got a new boyfriend and stopped going partying with her and our friends, i tried doing other stuff, but everytime we would speak, she would try to get me to go out with her to parties, when i clearly told her i do not want to.) it was just stupid. after all of this happened, especially after i got a new boyfriend, she started to treat me really badly. And then she went and got a boyfriend herself afterwards!! she even called me flat chested. (my breasts are fine to me, as they fit perfectly with my body size, even though they ARE small.) Do you think she is jealous of me? Knowing about her eating disorder and her desire to be skinny, I think this is the reason she treated me so badly, I have done nthing to hurt her. any ideas?