@KathyClism Yes, that's what bothers me as well.
Sure, to them she's just a pawn they want to use.
There's still no reason to be this abusive. It feels like they're being evil just because. Even if they are born sadists or something, you'd expect them to torment peasants that have no means and won't be missed or similar.
Adele is still, for all intent and purposes, a public figure. She goes outside, she attends school, she talks to other nobles. There's no reason to abuse her so much and risk that their misdeeds somehow spread outside of the family. Remeber she was hit and had to go to an event with a bruise on her face. Why would you ever do that? That's stupid, you're just risking exposure.
I feel it detracts from the story honestly. Feels like the author is trying to be dramatic just because. The author could have given her family an actual reason for them to hate her, or at least make most of the abuse only psychological. Like this, it just feels recklessly stupid on their part. And do note, the brother is so insane he goes and blows up a door and a wall of their estate right in front of the father, and the father doesn't really say anything to that.
I get what the author is going for, but he's really asking me a strong suspension of disbelief. More than cold and abusive, the family seems batshit crazy and you have to wonder why they're all still alive.