I’m sorry for what you all went through.
I found out not many years before my elderly mother died, that she and her sister had been repeatedly molested by a “hired man” and the girls were too afraid and ashamed to tell their parents.
Both of them became alcoholics and my mother had a very tormented life in many ways and our whole family was pretty messed up. Finding that out explained a lot.
Yes, finding out explains quite a bit. If I may offer one bit of unsolicited advice, let the pieces fall where they may and don't look for the missing ones to try and complete the puzzle. It'll just drive you crazy as it did me. I'm still (obviously) working on letting it go.