I found out there were others before and after me. What should I do? TW-SA

Background; I was 16 when my mother’s boyfriend at the time (husband later) started grooming me. I tried my best to make up excuses for his behavior because I didn’t know better and I didn’t want to lose my family.
A couple of years before that, my sister had filed a police report on him for SA but to this day I have no idea what actually happened. She was 14 at that time. She left home for few days and then he (the offender, aka mother’s boyfriend) got a lame 1 year restraining order from my sister and once it was done, the case was closed and he moved in with us.

I know that by law, I can still file my report (I have 1.5 years till I couldn’t do that). I knew it was only me and my sister back in the day. I met a person who became a dear friend and I asked him (considering their background) if they can see if there were others. The only way to know this is if my mother’s (now) ex husband had other complaints placed against him in the police systems.
He dose. Way before and way after me.

I assumed this would be the case, I just didn’t think I could ever verify this. Now that it is fully confirmed, I’m feeling a need to do something.
Should I file my police report again? Should I go after the police? Should I go to civil court?
I’m not looking or revenge anymore, and justice simply doesn’t exist in our world.
I can’t stop him from hurting other underage girls. I want my powers back. I want to be the woman who can hold little me’s hand and tell myself I fought for her and I did something.

Realistically, he won’t be charged (most likely) cause our system is rotten to the core. My hope is to at least reach to sit in front of him and take my power and voice back.
I want to sue the police (it is possible) for completely ignoring a child predator and letting him keep going and destroying many other women and girls over the years.
I want to be able to stand tall and prove I was right all along. To prove to that little girl I used to be, that no matter what she was told, she and I are not liars.

I’m just not sure how to handle all of this. I am strong enough to go through with all of it, part of it maybe, I don’t think I could live with myself having done nothing.
Thank you so much for reading