How to get my friend back?

Ok today I got a message from my best friends myspace but I don't know if it was her or her other friend but it said stuff that hurt my feelings bad and she said she WAS talkin about me behind my back and said some other stuff that hurt me SO BAD!! And it just makes bad things go threw my head and I dont know what to do!!

You said she's your bestfriend.
Why not give her the benefit of the doubt and talk to her about it?
Try not be accusing just ask her if she sent the message.
Until you do this, lets try and get the voices in your head to stop... They dont really know what is going on...
Once you have talked to her, and if she did say those things try and find out why she said them and why she's upset with you.
Now I know this is hard but this really isnt the end of the world. If she did say those things then she is obviously not a very nice person and she definitely isnt your best friend. Yes the loss of a close friend is hard, but you will move on, and you will make new friends.

Honestly, you need to think about this rationally... This is your bestfriend. Even if she had an issue with you, why would she use myspace as the venue to inform you? This sounds like a stupid prank played by someone who wants to hurt you and is jealous of your friendship...