I've read all your replies and I do agree with what you all have said and thank you for the advice, I am just going to let her down easy, I don't mind being her friend, she says that I am her best friend and all that, which is really sweet, it's just what she does that annoys me that she doesn't notice.
I've phased people out before, I'll just talk to her less and less and say I am busy when she asks to come over.