My sister is in this position as I went NC with my mother 1 year ago this week.
Just so people understand, the decision to go NC was not an easy one. I endured 41 years of being treated like the shit on her shoe, but nobody would ever see it from the outside as she was such a charmer. I don't remember ever being picked up, hugged, had my hair ruffled, put to bed, read a story, told I was loved. Ever.
Fast forward to when I was 13 and my parents split up. I was doing most of the housework and also cooking and ironing for her, whilst enduring a host of men she was fucking, including a married man. One time I came home to find him in the living room with his wife and daughter and my mum and they were all fighting over him. I had nits, scabies, ringworm, cardboard in my shoes. One of the boyfriends tried to abuse me. I slept with a cupboard wedged up against my bedroom door.
That was all forgotten by my mother when she met my step-father. She re-wrote history and then set about abusing my step-siblings. Screaming in their faces (always when my stepfather was absent) getting them make their own food, when the boy was 11. Eventually sent him off to boarding school.
My two other siblings were treated much better. I was the scapegoat. In 2010 she took my two other siblings on holiday without me, and it was like a family rule that I could be slagged off without any repercussions. I was the target. I didn't do anything wrong. The only time she was ever interested in me as a person was when I achieved something. Two degrees, turned up to both ceremonies lording it when she had done zero to help me get through school. Never once asked me about homework. Refused to go to school to get me free school meals as she clearly couldn't be arsed. I stole food from people at school.
Occasionally she would phone me up to abuse me and belittle me, often that was when I was in work.
To the outsider everything is fine and I am a cruel bitch for going NC. My mother is currently spreading it around the family that I am a mentally ill drug addict and very promiscuous. She's telling people that the last time we spoke I told her that she was a "lazy fat bitch". People believe it. Those people can do one, I don't care. Fuck the fucking lot of them.
If my sibling attempted to get me to speak to this evil sadistic bitch she could do one too. I appreciate her restraint and her respect for my choices. She's getting it in the neck now mind, a scapegoat once departed leaves a void. Beware OP!