Thank you for replying everyone. I'm in a low place today and I feel as though I've reached a point where I need to do this.
My mum is a lovely woman. She is kind and she tries to please everyone around her. She's generous and she's always helped me financially when I was younger. We don't talk of the past and I have not spoken to my father since the day she left him, not only because I'd be too terrified to do so but also because he never tried to.
As an adult I can now understand how hard it must have been for her, and how easy it is to slide into an emotionally abisive relationship. I ended a relationship with a man who cheated, lied, gas lit and stole from me 3 years ago. I've experienced bad relationships and I get that she didn't believe she could leave (she thought he'd kill her).
But In the past, and as a late teen, I've explained how my childhood hurt me...She has said things to defend herself and minimise the abuse that happened. I don't think I can forgive her for this. I have so much resentment around the fact she had her happy childhood and yet mine had no happiness, it was just pure fear.
I'm sobbing myself silly right now trying to get this all out. On the outside I'm probably functional, I own a house, have a pet, have a car and a decent job. But I'm chronically single. No one can love me because I'm crazy in relationships because I just can't cope with them. I have suffered from depression for most of my life and tried to end my life in my early twenties. I yearn for children and a happy stable relationship but I don't think I will ever have that opportunity.
Blue - you're doing the right thing by your children. It'll be tough but they will thank you for it. 
Arsenal, thank you for replying. I'm not a mother although I'd love to be. But now I think about my childhood from the perspective of myself as an adult it makes it worse...I can't imagine not protecting my children and letting them experience their childhood.
Crazyduchess, good luck to you and I hope this helps you. Did your mum contribute toward the abuse? I know my mum tried to make us happy but ultimately we were terrified. She uses the fact that she'd take us to the park and buy us treats as a way to avoid the truth. This is what makes me feel so guilty at the thought of cutting contact