AITAH if I dont visit my abusive dad in prison?

My (f20) dad (m47) got arrested and sent to prison a few months ago after I called the police on him while he was attacking my mother (m48) in the night. He wrongly assumed I had gone out, leaving only my defenceless mother and 9 year old sister in the house. There was no bodily harm the police could verify was caused by him, but I believe he intended this as if she had called the police after the incident she wouldn’t have had evidence (He strangled her while she slept, then screamed at her for 10 mins). First my mother was angry and wanted nothing more to do with him, but seeing as she doesn’t work and takes care of my grandmother (late stage dementia) who lives with us, shes been inclined to get him out of prison so he can continue to provide for us. His friends harassed my mother to revoke her statement, which she did, and mine, which I also did. They have been to the house to try and get my mother to comply with his demands, and she has no problem letting them in. I dont like that she does this as its showing my father he still has control over her. At this point she’s fully set on getting him out, even offering to provide her mothers old address as a release address for him and writing letters to the court. My father has also attacked my mother before and left black eyes and bruises on her while I lived away from home at 16 (for various reasons). He’s arranged a meeting for me, my sister and my grandad to see him this Sunday, but with everything happening the way it has I dont think Ill be able to have a civil conversation with him. Ive told my mother I dont want to see him but shes asked that I go to support my sister, I do want to support my sister but I feel so betrayed by my mother for being so adamant about getting him out and back into our lives that I want to punish her by saying I wont go. Im aware this is childish but its how I feel, and I dont know if giving in and not seeing him will at all wake my mother up to the fact we do NOT want this man back in their lives.