I Transmigrated into the Book as the Wicked Second Female Lead

I am the vicious second female lead in a book.

I constantly manipulate and put down my boyfriend, who works himself to the bone to pay for my medical treatment.

In the end, I cheat on him with a rich second-generation heir and dump him.

As it happens, my boyfriend is the male lead of the book.

Later, he is saved by the female lead and builds a business empire.

At the end of the book, he kills me to avenge himself and secure the female lead's happiness.