Please take blondie's advice; get info on codependent/enabling family relationships. Your mother knows exactly which buttons to push with you, and since you're the only one who will still bother with her, she figures she can continue in the same way as she always has, and that you'll always be there for her.
Being related by bloodlines does not mean a person has to put up with abuse, be it verbal, emotional or physical. It seems as though your mother has years of experience with emotional and verbal abuse, and it's because she still has people around who put up with it. Of course, it's difficult because those bloodlines sure are hard to ignore, but in a healthy family relationship the children are not made to feel guilty about growing up and moving on with their lives, nor are they made to feel responsible for their parent's happiness/health/emotional well-being.
I've gone through some of the same issues with my folks, but you have to come to the point where you realize that you are enabling this type of thing by always being there for them in spite of such abusive behaviour. Why should your mother change if there are never any consequences to her actions?
Your mother has chosen to act this way throughout her life; you now need to create a safe spot for your own heart and emotional well-being, as well as for your family.
Take care and keep us updated.
Ac