My heart goes out to you, @tympanic - and all the others on this thread who have been so badly hurt and let down by their mothers. I can empathise because, whilst my mum wasn't openly vicious and poisonous as too many of your mums were, she was emotionally neglectful of me.
I was bullied from the age of 10, when we moved to a small country village, where I simply did not fit in - I didn't have the right accent, hadn't lived there for umpteen generations, and was a quiet, bookish child. I remember going to my mum in tears, when I was being bullied at school, and her response was to tell me that sticks and stones would hurt my bones, but calling names would never hurt me (the bullying was name calling and exclusion), and that I should simply ignore it and it WOULD stop.
I was left feeling that, if the bullying continued (which, of course, it did), it was my fault for not ignoring it well enough, and that there was no point in going back to mum to tell her that the bullying was no better, because I would just be brushed off again. I also felt there was no point going to the teachers at school - after all, if my own mum didn't care enough to help, why would they? And if I had toldl the teachers, and there had been a backlash from the bullies, I was 100% sure that I would get no back up from my mum to deal with it - so I was too scared to tell anyone.
By the age of 14 I was clinically depressed (though I didn't actually realise this until I was in my 40s) - I was having suicidal thoughts - and it has left me with depression, anxiety and low self esteem that still blight my life.
That's not the only example, though it is the worst. She openly favoured my sister - for example, dsis got a £250 oboe for her 18th, I got a £20 clock radio. We had to share bathwater (due to an inadequate water heater) and dsis always went first, so she got the clean, hot water, and I got the cooler grubby water, and had to clean out the bath and tidy the bathroom afterwards too. When I asked if dsis and I could take turns to go first, mum refused point blank. When I asked mum not to smoke in the car, because it made me car sick, she said it was dad's pipe smoke, not her cigarettes, and refused to stop.
I have, on the odd occasion, tried to tell her how she made me feel, when she ignored me and brushed me off, but her attitude is that it was a long time ago, no point discussing it now - in short, I get brushed off again.
She talks about how proud she is that her daughters are her friends as well as her daughters - I think she has no idea how much she has hurt me, or how much anger I still have. She does talk about how she'd like to see me more often - I am just glad that I live in Scotland and she lives in Berkshire, and with the ties of home and dogs, I can't get down there very often.
I wonder if she realises that I come as infrequently as possible, and would come less, if I could?