Hello rainy: I don't know as I really have a lot to offer here. But I saw that no one had replied to your post, so I thought I would. What you wrote, with regard to your friend, sounds to me (given my limited knowledge of the subject) like pretty-much textbook BPD behavior. Earlier this morning, as it happens, I was watching a few of California therapist Kati Morton's YouTube videos regarding BPD.

I can't really give you any authoritative advice with regard to how you can help your friend. My gut-level reaction is, quite honestly, you can't help her. She has a pdoc & a therapist. It is their job to help her. You have your own struggles. And as you wrote, your friendship with this person is taking a significant toll on your sanity... the stress is killing you. This being the case, you have to take care of yourself. It accomplishes nothing if you allow this person to drag you down.

Yes, it would be marvelous to imagine you could continue to be a friend, support your friend, & contribute to her ultimate recovery. That is the dream. But, from what you wrote, the impression I am left with is this is not the direction in which circumstances are heading. What's happening is your friend is not getting any better (at least not yet.) And you are being dragged down into the vortex of her illness.

Ultimately, in my opinion, each of us who struggle with mental health issues must realize that those around us have their limits. And it is up to us for figure out some way of not continually transgressing those boundaries. If we cannot, or will not, then those around us must do what they must do to protect themselves. From my perspective, this is what it is time for you to do.