I feel like I need to cut ties with my whole family

Trigger Warning; This post contains themes of pedophilia and child abuse.

I am aware that my family are extremely toxic and it has a negative impact on my mental well being.

When I was a young child (8 or 9), my mother used to hang out with this man. He was not my father, who she was and is still married to and living with, but every so often she would visit this guy at his house. On these trips she would bring myself and my sister along with her. We would sit in his living room and watch television while my mother and this guy would go upstairs. When I was older I found out that they went upstairs to have sex which the guy paid my mother for. She was a prostitute and she would bring her two young daughters to work with her.

Now I have asked my mother why she did this. She claimed my father knew about the whole arrangement and we needed the money. I asked her why she left my brother at home with my father and brought myself and my sister along when we could have also stayed at home. She has refused to answer this question.

At some point my mother decided to stop seeing this man and she told myself and my sister to stay away from him. My sister did not. My sister also encouraged me to go visit this man behind my mother's back because he would give her money and sweets. In exchange he would kiss her and show her his penis. He would also show her porn. He was a pedophile.

He was also sexually abusing other children in the village. When it came out I was interviewed by the police. I had to give my statement in the presence of my father, they did not give me any other option. The police did not know that my father had told me to lie about knowing this man in order to protect my mother. Me and my sister gave conflicting statements which could not be used as evidence. From statements given by his other victims, he was sentenced to four years in prison. He is free now, living by the seaside and the last thing I heard he was actually working with children as a lollypop man (crossing guard).

I recently lost my shit with my mother about this whole debacle because she was trying to play happy families. Word got back to my sister about this argument and she said I was being a bitch. I think I have every right to be angry and I am flummoxed by my sister's reaction.

My mother's refusal to tell me why she brought her daughters along when she slept with this pedophile just makes me think that we must have been part of the arrangement. I can't see any other explanation.