context: Sixty-year-old multi-billionaire Robert Miller manages a hedge fund with his daughter Brooke Miller (Brit Marling) and is about to sell it for a handsome profit. However, unbeknownst to his daughter and most of his other employees, he has cooked his company's books in order to cover an investment loss and avoid being arrested for fraud. As she thinks that the business is so successful, Brooke can't understand why her father wants to sell - and he says that he's started to feel old and tired, and wants to spend more time with his family. However, he has a mistress (Laetitia Casta) who is supposedly supported financially by him. Miller looks extremely nervous with the last meeting with the prospective investor.One night, while driving with his mistress, he begins to doze off and has an accident in which she is killed. Miller leaves the scene and decides to cover up his involvement to prevent the public, the prospective buyer James Mayfield (Graydon Carter) and his wife (Susan Sarandon), from discovering the truth.Miller calls Jimmy Grant (Nate Parker), a twenty-three year old from Harlem with a criminal record whom he helped get off the street in the past. After being driven home by Grant, Miller drags his injured body into bed at 4:30 am, arousing suspicion in his wife. The next day, he is questioned by police detective Bryer (Tim Roth). Bryer is keen on arresting a billionaire for murder and begins to put the pieces together. While all this is going on, Miller's daughter discovers the financial irregularities and realizes that she could be implicated and confronts her father.Jimmy is arrested and placed before a grand jury but still refuses to admit to helping Miller. Miller once again contemplates turning himself in. Even though Jimmy is about to go to prison, Miller tells Jimmy that investors are depending on him and that waiting for the sale to close before coming forward would serve the greater good. Eventually the sale is closed but Miller finds a way to avoid being charged. He proves that Detective Bryer fabricated evidence. The case against Jimmy is dismissed and the detective is ordered not to go near him. Miller's wife, thinking the police investigation is still on-going, tries to blackmail him with a separation agreement getting rid of his wealth. When Robert Miller refuses to sign, his wife says that she will tell the police that he got into bed at 4:30 am, bruised and bloody. In the final scene, Miller addresses a banquet honoring him for his successful business either because of his wife or in spite of her.He looks perfectly contented, but his wife and daughter don't look so happy, although they keep appearances up.
question: Who blackmails Robert?
answer: Miller's wife