Dear Poster, it's clear you are terribly unhappy and I'm so sorry. I think Dementia could be described as a long bereavement; you're losing the mother you knew, and in some ways a stranger is taking her place.
Dementia takes over a person, and sometimes they can become dreadfully abusive and unkind, even to their family members. It's not their fault, but that doesn't make the hurt they inflict any less painful.
My father used to break my heart with some of the unkind things he said to me, and after he died the doctor wrote Dementia on his death certificate. I wished I'd known, then at least I'd have understood. Now my husband has been diagnosed with Dementia, and now I understand that when he says angry and unkind things it's not him saying them. It's Dementia that's changed him.I cope by telling myself he's no longer the person I knew; in some ways a stranger has taken over his body.
It's so hard to ignore the nastiness, but ignoring that and not reacting seems the best way...sometimes I get glimpses of the nice person he was.
Can you tell yourself that your hair has nothing to do with your mother now? It's yours, to do with as you wish!