Then one day you notice that a certain person looks kinda familiar to you. To your horror you realize that the protagonist of your novels IS this person. You have been chronicling their life. You approach the person and strike up a conversation; only to realize that what is happening to him/her is what you are currently writing. You know that you have planned a significant hardship...let's say a really terrible one, that you know will make the book SUPER popular. It could make you TONS of cash, but it could totally ruin this person's life.
What do you do?