After Transmigrating into a Book, I Stole My Sister-in-Law's Beloved

The good news: I transmigrated into a book and got bound to a System.

The bad news: I became a minor villain in an angsty novel, and my System is a newbie that bursts into tears whenever I do something bad.

So I have to do bad things and comfort it at the same time.

I'm the novel's male lead's younger sister, and also its villain.

When the male lead gets beaten up, I join a crowd of thugs and cheer them on.

When the female lead is tormented, I make things worse from the sidelines.

When everyone gets a bad ending, I send knives to the screenwriter.