Attila thanks for your post, and yes I think that I am still stuck in the fog. She hasn't phoned me once since we had our email exchange in October, she has texted me a couple of times and I have replied, last night and today I've stuck to my guns and ignored her last message.
I never actually said anything about going NC to her, I just stopped calling/texting, it was quite a change as prior to NC I had been seeing her three times a week and speaking to her every day!
Am sure that she thinks it is because dh and I are back together (they don't like each other, and this was made clear in our email exchange in October), she would never expect me to do this off my own back (even though I did go NC for 7 months in my early twenties).
I have never had an apology, ever, for anything, and I know I won't get one now, she is certain that she has done nothing wrong.
I spoke to my aunt (mother's younger sister, who is also pretty much NC with her for past 18 months) and we talked a lot about what had happened when I was a child/teenager, and she said that she had spoken to mum about how she treated me so differently to db, and that she thought it was wrong. Mother just said that she treated me differently because I was difficult, and that aunt was wrong!
Also, aunt said that when she and mother had discussed me, mother told her that I had apologised for anything and everything that I had done wrong as a teenager, so aunt asked if she had apologised to me, mother was horrified and said 'why would I apologise to magpie, I haven't done anything wrong'.
And that sums it up really. I don't know if I should tell her why I and my family are NC, but she wouldn't understand or acknowledge that it had anything to do with her behaviour,so what's the point?
I have started counselling recently, and will be using that time to process my feelings about the past, better late than never!
My biggest fear is that I have left it too late for my children, they are too young to see through her superficial niceness, but have been exposed to her for several years, especially my eldest DD who is 12.
I am terrified that I parent like my mother, and I don't want my kids to grow up being scared of me and my rages 
like I was with her.
I am taking positive steps to do my very best to parent my children how I wish I had been parented, but am scared I will fail.
My immediate response to stressful situations is to shout 
, I tell myself that at least I don't hit my children, but that's just not good enough, I know I need to stop yelling, but don't know how, as it's all I know of how to mother.
I do cuddle my children and tell them that I love them, which is one way I feel I'm different to her, I don't remember ever being told that I was loved, and I never used to be cuddled (apparently I rejected her from an early age and refused to sit on her lap unless I was really ill).
Sorry, that was longer than I intended. I will have a read through others posts and see if I can offer anything useful.