Please try and find a different counsellor, perhaps someone who uses CBT techniques or maybe take the Freedom course? You can't do this on your own and you really need to learn some techniques to free your mind and thought processes and retrain your emotional brain.
This relationship with your Mum is so toxic, so awful and so destructive but it defines your life, doesn't it?
If you cut her off then what will you do? How will you feel? Who will you be?
This crippling guilt at the thought of being happy says that the familiarity in being UNhappy is almost too much to give up. It is sadistically comforting because you know the patterns, you expect the behaviour, you get that awful cycle every time but at least you know where you stand.
The rest of the family has given up on her so I bet there is the child in you screaming for recognition that you are better than them, a better daughter, a better person because you won't give up on her.
That isn't strength, that is addiction. I am so sorry but you are enabling her behaviour and you are failing to protect your own family and life if you are allowing her to still dominate every waking moment, every decision you make and every interaction you have.
Does that make sense?
The sad thing is that it isn't your Mum who will steal your daughter, it will be your inability to protect yourself and therefore protect your daughter from this hideousness that will lead to losing your children.
Is this the kind of relationship they should think of as normal? Is this the way you want them to expect to deal with horrible, evil behaviour? Do you want them to learn to stand up to bullies or to take whatever they are given?
Being selfish is not about choosing to cut her out. Being selfish is not refusing to call her back. Being selfish is not about saying no to the shopping, the dogs, the appointments.
She will accuse you of everything. She will try every tactic you know and some you don't. Does that mean she cares about you at all? Does that mean she needs you? Does that mean she loves you? Does that mean she thinks you are special??
Be honest with yourself. Really honest. Is any of it about you?? No. This is all about her, about her power, about her control and about her feeding off you because she can. Because you let her. Because she has brought you up to be that person, that battery fuel that life source for her evil nature.
Putting your mental, emotional, physical health first and enjoying a healthy relationship with your husband and children is not selfish. It is essential for all of those things to survive. For you to survive.
Please get some help. Please take whatever validation you need to make this enormous but lifesaving decision.
She is NOT your responsibility, whatever you might think.
Good luck