Why do I still feel hatred and rage towards my mother even thought she has tried to reconcile with me?

Through out my childhood my mother always yelled and screamed at me and said hurtful things as well. She was always angry at me and called me names when I did not understand something in school or when she helped me with my homework. There was constant tension, anger, impatience and frustration towards me. About 7 years ago my mother went through an emotional time dealing with her family and she started discussing mistakes she made in my childhood. She has apologized for what she has done and has told me that her anger was not because of me but I still feel rage and hatred towards her for ruining my childhood memories. Part of me wants to forgive her now that I'm older and understand how horrible her childhood was and the other part still despises her. She wants to build a new relationship with me but I still see her as that angry,cruel and bitter woman she once was. Any insights?