Okay. this feels awfully similar to that infamous dual protagonist dating sim Joubachi no oubou... (for the love of god, don't taint your eyes with this game. its an 18+ ero otome)
Where we get sad and pathetic protagonist Menou and seemingly villainess protagonist Kaguya.
Depending on the heroine you play, you either end up being subjugated to a life of hell being a tool and get attacked by three dudes. Or you get to play as the stronger heroine and (depending on the route) may very well become this sadist to one specific masochist...
The game is hell and for some reason, the choices she puts herself to reminds me a lot like what happens in this story.
Like, that's hell if you get reincarnated to a game world like this.