Oh good, if she has sisters, let them handle it for a while. Meanwhile you might read up on borderline personality disorder - that might help you in future dealings with her.
Also - find yourself a "mom" elsewhere. My good friend grew up with a stepmom with borderline personality disorder - mild, but still very problematic. (Her bio mother died when she was young). She made good friends as a young adult with an older woman who became a mentor and more of a mother figure for her.
