Repost for visibility: Recently learned about a dark family secret from my husband's side, who are all Mormons. My husband and his brothers repeatedly raped their sisters and their parents covered up the crimes and threatened the sisters to keep silent.

Content Warning: SA

I think I'm going insane here. Someone, please help me understand this. I recently found out that my husband of 13 years of marriage is a rapist. My husband's family is Mormon with 9 children. They are all adults now, with most of them having spouses and children. A few days ago, there was an argument between my parents-in-law and their adult daughters. The argument was bad enough that the daughters decided to spill the family's dark secret to the rest of the family (including the spouses and children). The dark secret was that there had been several sexual assault within the family that had been covered up for years. The older brothers (including my husband) had repeatedly molested and raped the sisters and younger brothers. The older brothers also snuck into the sisters' room at night to touch them while they were asleep. The sisters asked the parents for a lock on the bedroom door, but the parents refused. The sisters had to steal a door knob with a lock somewhere to replace theirs, which got them in trouble with the parents. The sisters then used a chair to bar the door to prevent their brothers from sneaking in. They heard the brothers trying to get in and were terrified. Once again, they got in trouble by the parents for blocking their doors. The brothers had also raped the sisters during the day. They pinned them down and forced themselves on the sisters. And this had happened repeatedly. It didn't stop until the sisters were in high school and were old enough to make a serious threat to stop the brothers. The worst thing is, the parents knew about it. They tried to cover up for the brothers. The parents forced the sisters to keep silent on it to protect the brothers until just a few days ago during their daughters-parents' argument. The mother (my mother-in-law) accused the sisters of asking to be raped and calling them evil.

I am so confused by this whole thing. I've been married to this man for 13 years. I have two daughters with him (12 and 9). I never knew about this until now. I am even more confused by his whole family's response to this secret. My parents-in-law and their sons are shunning those sisters and are planning on relocating as a group to protect themselves from if/when the sisters go public with the information. I haven't talked to the wives of those sons, but it seems like they're gonna go along with their husband's and parents-in-law's plans, and take their children (including daughters) along, as if the biggest threats aren't the rapists, but the victims of the rapists. They're all Mormons. Including the spouses of the brothers. And they're all stay-at-home moms. I'm not Mormon. I'm atheist and a feminist. Also, until just a few weeks ago, I was the breadwinner of my family for years and had always had a job. I'm so confused by all of this. I can't talk to anyone. I have one sister who I know would be gone the moment she learns about it because she was an assault victim herself. I dont want to retraumatize her because she is still in therapy for it. So all I have are the people who know about it, whose responses and reactions are so bizarre, it makes no sense to me. I'm still processing what to do given my situation, and how to best move forward with my daughers' safety in mind. Yet these family members have been messaging me, trying to tell me not to leave my husband. As if ending a marriage is the bigger sin. I'm so confused by how these people are reacting to this information, as if an incestuous rapist isn't a big deal. I am so confused as to why they're protecting the rapists and being more concerned about them over the victims. I checked the limitation of statutes in my state, and it's way past that now, and I don't think the sisters would report the rapes to authorities. And I wouldn't want to do anything that the victims don't want to do. But I am still bothered nonetheless. I can't get the image of my husband raping his sisters out of my mind. I can't get the image of him sneaking into their rooms at night and feeling up on them while they were asleep. I can't stop thinking that if he did this to his sisters, how can I believe that he wouldn't do this to his daughters? He only stopped when the sister was in high school. Which means that he was probably an adult when he was still raping her. But I am confused because I am surrounded by people whose reactions and responses to this whole thing don't match up to what I'd expect and think people shpuld respond and react to incestuous rapes. It doesn't make sense! It's as if I'm the crazy one for being this freaked out about it.

Edit: Instead of responding to everyone, I'll just update it here:

I talked to my husband, and he admitted to everything. He said he was relieved that it's finally out because he knew it would come out one day.
I do not trust the sisters who were victims. I reached out to them, and their responses confused me even further. They expressed regret for outing their brothers and suggested that I not leave their brother. I am shocked that they aren't thinking about my kids but are worried for their rapist brothers.
I talked to my daughers. Both said nothing inappropriate happened to them. I've always kept a watchful eye over them, including when they're around their dad, just because I've heard enough about sexual abuse within families.
To those who said I should have known since they're mormons: despite being married to a family of Mormons, I had always had limited interactions with them. I didn't agree with their religions and lifestyles, especially with how differntly they treated women compared to men. I have daughers and i didnt want them to grow up thinking they're lesser just because of their gender. Also, every family event that I attended always felt awkwardly fake. In the past, I couldn't tell my husband that he can't interact with his own family, but I did explicitly told him that am not comfortable being around them.
I am shocked because I was married to this guy for years. He had always been committed to me and the relationship. Never cheated. Never looked at any woman. Also, he left his church to be with me. He claimed to be a feminist and supported me in raising our daughers in a household that focused on women's rights. So it was shocking that all that was a lie and I never really knew him.
I didn't say I'm not going to leave him. But I am shocked. Also, i am currently unemployed (recently quit from a stressful job and was in the process of looking for a new job to be able to be there for the kids more). Also, i don't have family with whom I can turn to. My dad passed away years ago. My mom is not well mentally. My sister is still in therapy, and she lives far away. So, whatever I plan to do, it will be a slow process. Even worse is that my husband is more knowledgeable about the legal system. He attended school to be come a lawyer, but dropped out a few years ago.