Fake System, Real Revenge

Synopsis

I somehow ended up inside a fantasy novel. My role was the vicious female villain who constantly bullied the princess. The system instructed: [Follow the plot if you want to go home.] So I did exactly what the story demanded: poisoned her, framed her, and stole her man, without missing a single step. Soon, wanted posters with my face covered the entire kingdom. I smiled and asked the system, "That should be enough, right? Time to send me home." The system fell silent for three seconds before crashing, leaving behind one final message: [Warning! The storyline has deviated! Please uncover the truth!] I followed the script exactly, so how had the plot gone off course? In this story,who was the real villain all along?