The antique girlfriend of a chaebol heir

A traditional, talented, and icy beauty from Jiangnan VS a possessive chaebol heir
Shen Ci, the eldest daughter of a prominent family in Jiangnan, was frail and sickly from a young age and had never stepped outside the Shen family mansion. In her more than twenty years of life, she had seen more doctors than men outside the family.
After her life ended, when she woke up again, she found herself in a storybook, becoming the villainous female supporting character who took credit for the heroine's life-saving grace and used that gratitude to blackmail the male lead into becoming her boyfriend.
In the storybook, the original owner of the body caused countless troubles in order to truly rise to power, but ultimately ended up being expelled from school and his father's business went bankrupt.
Shen Ci decided to first keep the male lead calm, avoid causing trouble, not compete or fight, and quietly remain a background character. Once the male lead took the initiative to break up with her, and once the real female lead from the book appeared, she could leave and live peacefully in this new world.
She was exceptionally good at waiting. She had waited for over twenty years in the deep courtyard of her mansion, and patience was the one thing she had in abundance.
However, when the true female lead in the book finally appeared, Shen Ci felt the time was right and couldn't help but cautiously propose breaking up.
Inside the room, the male protagonist, panting heavily, pinned her tightly against the wall, a chilling undercurrent surging in his eyes, his voice hoarse and dangerous:
"Do you still dare to bring up breaking up?"
On this very day, Shen Ci and the half-mad male protagonist almost met without any matchmaker.
Shen Ci then realized with horror—
What she got was not relief.
Rather, it's the moment when a madman completely tears off his disguise.