I think the best way to frame this is:
Imagine if you saw a woman being assaulted, raped, strangled or murdered. What would your reaction be? I assume you, and the vast majority of people, would feel very worried, concerned, panicked, want to help her, report it to the authorities, make it stop.
When your husband sees this happen to a woman, he enjoys her suffering and has a wank.
Some people (the “kink-positive” crowd) might try to convince people that “it’s just a fantasy, it doesn’t mean he really wants this to happen, don’t kink shame him!”
Bullshit. If a man had hard drives full of cartoon images of child porn, we wouldn’t say “chill out, they’re not real, it’s just a fantasy, he should totally be allowed to work with children, I’m sure he’d never really act on it!” - why should it be any different when he has hard drives of women being tortured and murdered? Whether the torture/rape/murder is real or not, his enjoyment of it is very much real.
Like other posters, I suspect this is very much the tip of the iceberg. If he is watching such degenerate, depraved material like this, then he has already escalated his porn habit to an unacceptable (and potentially criminal) level. It isn’t really much of a further step to child exploitation material, and I wouldn’t at all be surprised if he had already accessed this.
I’m truly sorry that your husband has chosen to do this - it’s completely unfair for you and your family. I personally could not bear to be with a man who behaved in this way, but I understand it must feel like a bombshell has been dropped on you and completely overwhelming.
If you do choose to leave him, please do it carefully - who knows what he’s capable of. You say you feel “unnerved”; listen to your gut instinct, it’s telling you that for a reason.