It's ok to be angry

Hi. I am 54, female from a middle class domestic violence family in NC. My father was a violent alcoholic for many years. He had BPD and extreme narcissistic traits as well as sexually abusing me for years. My family hid behind the Baptist church. My mother is a very passive church mouse who stood by her man until he died on their 51st wedding anniversary. I still struggle with CPTSD and BPD myself. I have 465 days recovery from opiate/benzos addiction. Anyway, my question is this: can you help me to understand why I feel such anger at my non-offending mother. She was born in 1929, and I grew up in the 1970s-early 1980s when church schools fought for their rights to operate without having to report anything to government officials and to keep the government out of their business. Plus, our church enforced the submissive wife model who prays for her abusive spouse to change, no matter how he treated her and any children. A lot of people I attended church school with were openly abused. Is it common for ACOA'S to feel anger at the parent who caused them to have to endure he'll on earth and allowed them to become so screwed up? how do I resolve This? She is a big PTSD trigger for me, although I love and pity her. She is sickly and in a nursing home, yet I panic every time I see her. I feel so guilty. Is this common? Any suggestions? She really is a good person, but made some horrendously hurtful decisions in life. She literally had no social support to leave him. Society would have shamed and rejected her if she had left him. She was also financially dependent on him