SOLVED. a kid trapped by a huntress who can glue creature body parts together?? [s]

[Antares]

I read some parts in a bookshop about two years ago
there was this kid who i think found out his mother's secret or something and crossed into another world
then somewhere around a third of the book he gets trapped by this huntress person thing
And there are mentions of a fox or a doe with a girl's head
The huntress made her I think by cutting off both the heads and then gluing the girl's to a wrong body, she said something about they are more obedient like that?
and mentioned she'd sometimes put animal hands on human bodies for lols and they would always be too stupid and useless?
apparently she cooked the girl/animal's meat for the boy when the girl god disobedient
What I clearly remember is that he got away from her by telling her about centaurs
And she was intrigued and made him help her turn into one
She cut off her horse's head but then when she cut herself in half
Instead of putting the thing that kept the bodies alive on her wound and attaching her to the horse the boy just kind of ran away

and that's when I really had to go home and I had no money to buy it and i can't find it now does anyone have any idea?

[Debbie is on Storygraph]

Sounds like The Book of Lost Things

[Antares]

Debbie wrote: "Sounds like The Book of Lost Things"

ah, thank you, that's it!