Cut off all family?

I’m in need of some serious advice. My two Neices, we’ll call them A and B. A is 10, her half brother sexually abused her and she told me about it. My other niece, B is 13 or 14 and she was also sexually abused by the same guy. He’s 16 I believe. A while back he was charged with sexually abusing a 6 year old girl. There was a CPS case opened but as far as I know, nothing is happening because there’s no proof and my family doesn’t do anything about it. My sister, A’s mom posted on Facebook how she loves her step stop (the abuser) she also posted pictures where A was standing beside him (AFTER the assault) A’s parents know about it, so do B’s parents. My mom also knows and says he’s innocent.

I’m not close with any of my family. My moms a narcissist and my siblings are much older than me so we never knew eachother very well. I have 2 kids and my husband and I recently made the decision to not allow our kids around them because if they are supportive of a rapist, then my kids aren’t safe. The problem is that I have 6 neices and nephews that are minors and if we cut off the family, we will need to leave them as well. None of them would beable to stay in contact with us, they do not have their own social media or anything and of course my family would hate us and forbid them from talking to us. I was raped by my brother at 14, so I’ve been through this. The depression almost killed me many times because of it and I’m terrified that if we leave.. they won’t be protected, just like I wasn’t protected by them.

There’s so much more information to this family. Honestly I could go on forever about the problems and why they are toxic. My husband and I have even contemplated getting passports and moving out of the country just to know they would never be able to find us again. But again.. how can we leave them?

What would you do? I have tried to talk to both of them, but they are still in the “it’s not really a big deal” phase and they laugh about it. I know it’s because my family is making it out to be normal but I am at a loss on what to do 😞

EDIT: the police do know. He was charged with the first one (I think he got off easy) but I do not believe they are moving forward with these cases. The reason being, they live in a HORRIBLE town. The sexual abuse people they have are bad. Most sexual assaults never go anywhere. It’s the reason my husband and I moved an hour and a half away, that town is doomed. Doesn’t help that my sisters are friends with multiple officers and they even get high with them!! It’s beyond messed up. I honestly think you could make a documentary on how fucked up my family is. I know we need to get far away from them, but it’s so hard to leave them behind