When I first started writing down my mother's unacceptable behaviour, it was only to record events from the past two years.
I need to update the document, which is on my computer, as more and more memories keep coming back of things that happened from my childhood to the present day. Through a child's eyes it seemed acceptable. For example, being smacked in the 1950s/60s was an "accepted" method of discipline. She last did it when I was at senior school, cutting my lip, because I was holding tennis racket grip near my face at the time.
I can't forgive her many outbursts/tantrums/lies, but writing down and continuing to has certainly changed my perspective. It's also been therapeutic, in realising that I don't want to repeat the cycle. Yes, I may now be an outcast to most of my family, but I'm preserving my self-esteem.
I believe that you can recover (if that's the right word) from this, but forgiving her is not the right way. Understanding why she behaves as she does may help. Certainly, an explanation of what your therapist meant is overdue. Also, as hard as it seems, walking away from an overbearing parent may be the only solution.