It sounds to me like you know exactly what you want and what you need. Perhaps you could give yourself permission to take care of YOU first, and your mother second. Remember that you are no good to anyone else if you don't take care of yourself first.
If you're looking for outside validation, I hereby give you permission to step away from your mother and her problems made by her decisions, take care of YOU and do what you can to create an emotionally healthy life for yourself and your family.