When the Heroine Falls for the Villain

I transmigrated into a cultivation novel as the handsome villain—and immediately discovered the protagonist's sister is no side character. She's a hidden boss: a yandere with godlike martial arts and obsessive love that borders on madness. Now she's set her sights on me. How do I survive when the heroine refuses to follow the script? The original story had multiple love interests, but she's rewriting everything into a possessive, single-heroine nightmare. My counterattack as the villain starts now!