When is she leaving?
You only have her word for it that others said you were badly behaved and what they actually did was probably agree with her to shut her up. You said yourself that your school reports don't back her up and neither do your memories, which are not made up.
I tried for years to find out what was wrong with my mother, why she treated me the way she did, why she was so negative about me and my siblings and why she seemed to revel in crisis so much so that she would set us all against each other just to create one. For instance she loved to tell my sister, who was struggling to get pregnant, how we had told everyone but her (which wasn't true) and how she was always the last to know. What mother would hurt one child just to get at another?
I've given up trying to understand. I pity her, I know she is sick, but I am not a qualified psych and if she refuses to even acknowledge that she has a problem then what am I to do? Lay myself open for more abuse?
It was one particular incident that broke the straw with me, the ultimate betrayal which I won't go into detail with but basically she created a crisis around me and turned many of my siblings against me by telling untruths and getting many many people hurt in the process. I realised then that she was also beginning to control her grandchildren - my nieces and I was determined that my own children would not live in her shadow.
I have tried time and again. I have written letters, sent emails, invited her to call and speak to the kids but she never does, instead she tells others how I have turned my children against her and keep her from them. I now will not have anything more to do with her.
Yes it hurts. These people are not just any old people, they are our mothers. We know that it should not be this way. I grieve for the relationship that never was. But I know that none of this was my fault. I was not the ugly teenager she told me I was, I was never in their way as I spent most of my life cooped up in my room, I didn't cost her the money she says I did as I even gave her my dole money. She nearly took from me my self worth, my confidence, my identity.
You can pity her and feel sorry for her but that will not change who she is. Whilst you allow her to abuse you she will do. Playing the victim is so very easy to do and allows for maximum sympathy - it's a wonder your mother hasn't told you that you've made her ill, perhaps that will come. In the meantime you have a child growing inside you who needs you. You owe it to your child and to your partner to concentrate all your energies on the life you have now.
You have not chosen to cast her out, she has chosen not to be part of your life by continually abusing you and criticising you. You can always leave the door open and say she is free to see you so long as she treats you with the respect you deserve. If she can't do that then she can take her abuse and destructive energies elsewhere. If you let her, she will drag you down to her level. The reason you don't feel you have the strength to deal with this is because she has taken it all. Don't waste any more on her.