As horrible as it sounds, there does come a point where you achieve a certain level of disconnect between your intellectual reaction and your visceral reaction, and become able to put the former above the latter. If you read about something enough, you will in time become - to some degree - desensitised to it; you have to be in order to do your work. Most of us are to some extent desensitised to a certain level of personal violence by our regular exposure to it in popular media - the same is true of those who elected to subject themselves to studying accounts of the kind of abuse we encounter in our sources. Having said that, I would be lying if I said there haven't been occasions when I have had to take a step back and say "yeah, I'm done for today" because a particular source - for whatever reason - has really hit me.

Part of the nature of our work though is trying to give life to the stories of the people who suffered these abuses and indignities; to give people today a chance to know them and their ordeals, however fleetingly and distantly, as authentically as we can, in the hope that knowledge of their suffering will help to prevent it from ever happening again (though sadly in my field, we know that all too many people are still victims of slavery and slavery-like practices). I am a religious man, and I should like to think that the work of the historical community in this life to those ends has over the years given cause for a few smiles of relief and gratitude in the hereafter.

Done properly, history about these topics ensures their suffering will not be forgotten and thus, never repeated. People will always make mistakes. It's our job as historians to ensure those mistakes are new and novel.