What would you do?

I have a friend who has been lashing out recently, and when i tried talking to her about her actions, she totally flipped out on me and told me that i am no better, that i'm a whore, a druggie, an alcoholic and all that. And now, she won't talk to me. This is my best friend, who i have known since i was 2, saying this to me. That is 14 years of friendship there. And i just don't know what to do. I have tried and tried, but she's treating me like dirt.

I have been giving her tie to vent, but then she calls me only to ask why i haven't been calling her or going over there. And she's all bitchy about anything i try.