Frick, the best advice I can give you as the mother of an extraordinarily self-centered 17 year old girl is to stay on the upper road as much as you possibly can. She is undoubtedly living her own truth and her own suffering without comparison to any other. By which I mean, you have your own trials and tribulations and hers most likely dim in light of yours, but she doesn't know or understand that. At least that is how it was with mine. So if I'd taken any expectation of compassion or plain decency for me as her mother out of the picture, we'd have avoided a great deal of the drama.
Infuriating? Frustrating? Yeah. I don't know how to help you just breathe through it, but it's what I wish I had done.
I've no idea if that is helpful or not, but hope that it helps that I can relate to that crazy place.