I have a comment... I guess we all have had "friends" who were not really friends at all.

I would ask you to stop and think, what does this person provide for YOU. I am getting the impression this is a one way street, with you suffering on the receiving end.

How to fix it? Well, that is tough. It may provoke guilt in you since you are obviously empathic and giving. But you are basically not her therapist or relative, and some distance may reveal quite a bit to you.

You could examine your responses to her, and stop reinforcing her statements. This would take time and effort, but if she gets no reinforcement and only silence from you, she may give up.

You could shorten your calls by excusing yourself from her when on the phone after a brief time. You could slowly not answer her calls ( I hope you have caller ID). She would then get the message more slowly and it wouldn't be a sudden thing on your part to distance yourself.

This is just a brilliant book:
http://www.ivillage.com/6-types-toxi...hem/4-a-283671
It is in paperback and not expensive. It is available used from Amazon for even less. You might find some hints in it to help you resolve this problem.