What Can a person think now to release things they did years ago when they didn't know better?

My mother died over 20 years ago. She admitted she was horrible & she blamed needing to work for the reason she was such a nasty bidch. She was worried at the end of her life she would have no money & be a bad lady. I would have never let that happen but she felt guilty for the way she treated me. I decided to just let her stew in her guilt &I was not going to play her games so I ignored her when she talked about being a bag lady. She was so abusive to me I could barely talk on the phone with her with out hanging up feeling devasted. ...I don't want this to be part of my life even though it happened so long ago......I want to forgive her &really released this.....I want to forgive myself for not knowing how to protect myself & be able to confort her without having her continue to be abusive. I just need to get this out my energy feild. How do I do that?