Idk who my parents are anymore....

I walked in on my dad molesting my 13 year old son in his sleep... I locked us in me and my daughter's room and called 911. My mom wants me to actually drop the charges because she's trying to make it work with my dad. I got in contact with my brother. He stopped calling and coming home after he moved out at 20. I needed to know if my dad had done something to him. At first when I asked he tried to dismiss me and hang up but then I told him how my son had started having accidents a week ago and when I went to wake him up to pee at 3am our father had his hands down the front of his nephews pajamas.... My brother went silent and sighed. He told me EVERYTHING! That dad molested on him from when he was 12 until he moved out. When he got strong enough to fight back our dad got his friends to help him take advantage of my brother. How he would be crying after and our mom would tell him to shut up and stop crying. He said he told mom many times and she said not shut up about it and pretend it didn't happen... I hear him getting choked up and told him he doesn't have to talk about it anymore. He said he's so sorry about what happened. Who are my parents.... The ones who raised me and red me stories are now the reason my son has to sleep in my bed because he's scared. How could I be so fucking stupid! How could I miss the signs? My son started having accidents and for a second I thought maybe it was just wet dreams. That was a huge red flag in my face that I missed! Who are these people.... Idk anymore... My son asked me today why grandpa did that to him and I said because he's disgusting. I know it may seem inappropriate for him to sleep in my bed but he's so traumatized rn... My 4 year old already shares a room with me and has a toddler bed but since big bro now sleeps in the bed, she wants to. My son is embarrassed about the whole think and everyday asked why grandpa did that and give him the same answer. He's been having accidents in my bed too and getting me and his sister wet but I'm not worrying about it(I did hear if stuff to wear for that called drynites. Opinions on those). I will be putting him in therapy but he seems to think he's at fault. I'm the one who missed the red flags.... I just.... Every positive memory of my parents ever is now turned dark....