Hi Rachel,
Please keep in mind that I am NOT a doctor and have no formal education, but learning about abnormal psychology is a hobby of mine. I would recommend getting your mom to see a counselor or psychiatrist. The symptoms you describe sound a lot like personality disorder, like borderline personality disorder. Here is a link that might help. Anyway, please keep in mind that this is only a suggestion. Good luck.
Personality disorder - Wikipedia, the free encyclopedia