Newly aware of old circumstance

My husband and I recently learned from his twin sisters that both of them had been abused by my father-in-law. When they were young, and up into when they were around 12, they said, he would come into the bathroom after they showered to “make sure they were dried off.” It stopped when they started locking the bathroom door. They had never even spoken to each other about it, and their stories were identical. I’m horrified and angry. My husband is the same. I don’t want to talk to him or have anything to do with him. In fact, I would prefer confronting him. But the sisters don’t want to bring it up, and I feel like that is there call. I don’t know how to respond except to completely cut him off.

C- Found out both identical twin sisters had dad come into bathroom with them (separately) to make sure they “were dry”
T – Father-in-law is not someone I want to associate with in any way
A – Won’t answer the phone when he calls
R – Cutting him out without any resolution

I just don’t know what to make of this. I’m so angry with him and truthfully, with my mother in law. He professes to be a good Christian and they were both very protective of the girls with other people, no sleepovers, etc. I’m heartbroken for my sisters-in-law.