Best Friend Problems, Help!?

[Ashley xD]

Okay me and my best friend Sara have been friends for 4 years... kinda. Were in High School now and well were just turning out to be different people. I still lover her I want to be her best friend but she makes it extremely hard.
Like I liked this guy... He's not the best guy, he has gauges and hes into drugs for recreational use. I know that, she knows that, everyone knows that. I like him anyway and it's not like I'd do that or he'd even go for me, but point aside she trashes on him every chance she gets.
Shell gone on for hours about hes ugly and his gauges are disgusting and how could i like someone as nasty as him. When honestly he's not bad looking she just does it to piss me off, she does and says things like that all the time. She'll hack into my facebook account and post stuff from it or get on my Twitter and DM the guy i like and Tweet stuff at my other friends which I would never say. I don't know what to do anymore.
Im building up this resentment towards her and I can't help it. She can tell that im getting mad but she wont do anything to help. She wont change the way she acts I've asked her to.

What should I do?