Surf - I can't remember exactly how or why I finally 'never went back'.
I left in increments - lived with my mother's sister for a while while I was working near her, then moved into a house with some other girls (that was when the pressure started big time), then moved to Uni much further away. Went home during vacations and found work but then started finding jobs near Uni instead. Found a job that required me to work over Christmas then got fully involved in my life away from home.
I didn't 'plan' it but I'm sure my subconscious knew more than I did!! I experienced so much verbal cruelty but I didn't know that's what it was - it was just 'me' being a terrible person all the time, never being able to get anything right, never getting approval, always trying harder. I felt so sick at home yet I continued to go back, doing what was expected, trying to be 'good'!!! That's so sad (in all senses!). I had no idea what my feelings were or what they were telling me.
My mother drove me round the bend. I remember I used to think she'd say black was white if it suited her. Compromise didn't exist in her vocabulary. And everything had to be kept secret. Oh, I was so loyal.
I tried to get help for her (for what I'd now describe as narcissistic rage or hysterical paddies or hissy fits but appeared to be nervous breakdowns - always afraid that she'd 'crack' if pushed too far by my attempts to establish truth or reality!!) - but it just led to further recriminations and the most astounding lies.
I didn't know they were lies - I'd think I'd forgotten what I said or what I'd written ie I'd think there was something wrong with my mind - what I recognised in the film Gaslight and now know to be called gaslighting). I was 19 for God's sake (cj, when you write, you take me back to how things were then. Younger than that - 14 perhaps 16 - I did once just 'not know' where I was, who I was, where I was going. I knocked on someone's door - they didn't know who I was either!!

I have been so disciplined ever since - I NEVER let my guard down - I keep my mind in check ALL the time.)
One day (in my early 20s), in desperation, one time when I went home during a vacation and she was twisting and turning everything and driving me mad, I tried to phone the Samaritans. I managed to get through. I was sitting in a small room at the front of the house which wasn't used much. I only managed to make contact for an instant - my mother came in and broke the connection.
I put my head down on the stool in front of me. I cannot explain the noise I made - a very long aaaaaaaaagggghhhh of total anguish. I'll never forget.
And my mother twitched the net curtains and said 'What WILL the neighbours think'!
You gotta laugh!!!!!!!!!!!!! ?
A few years later, when I lived abroad, she acquired a postal vote for me and voted in my name!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! I always siad I should've shopped her. I dearly wish I had now!!!
I think I was very 'adult' from a relatively young age, but my mother was not going to respect or nurture the adult part of me. She did everything she could to destroy it.
So I'd suggest it's not as 'simple' as being 'adult' or 'growing up' or 'becoming independent'.
Just wondering how it's different...you need to develop more mental stamina than the average person, stronger boundaries, knowledge, wisdom, competence, resilience - and very good FRIENDS!

R