You can not tell the reader what happened but instead show a character's reaction to it. Let the reader fill in the details you suggested but did not explicitly write.
You can also 'cut to black' in a dangerous situation, again asking the reader to fill in the blanks. If/when they see the character later, what's important is that they survived and escaped, and again the details you offer help the reader fill in the ones you didn't.
Third technique is to have characters dispassionately discussing what is to or already has occurred and show that they are unconcerned with the dirtier aspects of the war or culture in question. Now the brutalities you've suggested are both anticipated and accepted by certain powers.
I've had similar problems writing for my d&d campaign. I want dark forces, but I also want a place of justice that is in danger. Something for the players to defend.
And I've never had to turn to SA. Yes, it happens in the world but I'm not going to turn to it for shock value.
Once I got dark enough to write about what a hag did to be 'gifted' a mortal child, and it was incredibly effective to be so gory and explicit after being vague about so much prior.
Holding back the details can be frustrating, but then making the reader swim in them after all the hints is a good payoff. And if done well you still aren't writing the assault itself but the preparation and aftermath, which is still bone chilling enough.
(In my game one of the characters was the hag's son, which he had only recently learned. The payoff for him was learning exactly how he was conceived.)