I'm going to confront my friend about her behavior and sever the relationship
What behavior are you referring to?
She always breaks her promises and leaves me hanging, when I never let her down.
It's okay if you prefer not to have someone as a friend, but you should try to work things out before you end the relationship.  Have you told your friend about times that she has let you down in the past?  If she never knew that she was betraying you, then it is unfair for you to keep getting angry at her.
That's a good point. I never considered that.
I'm glad to hear you say that. It's amazing what a dose respectul, empathetic conversation can do.