bestfriends

I have a bestfriend or at least i thought i did.  My so called bestfriends has beeen going around telling people my biggest secret.  When i try and confront her, she denys it.  What the heck am i supposed to do? She is so stubborn she wont accept the fact that she is a horrible friend.  I cant count o nher to do anything for me, she cant keep a secret, and when i tyell her something im uncomfortable about, she makes fun of me for it.  I have another friend and shes awsoem but she has a bestfriend that she aperently likes better and i understand that its just i dont compare to her bestfreind.  I am debating whether or not to talk to her about what shes doing but i hate fighting and i know shes not going to take it well.  I think im going to see what she does when i ask her something about it.  Well, crossing my fingers.