If you think your relationship with your sister is the worst there is, make sure to read Philippa Gregory's The Other Boleyn Girl. Set in 16th century England during the reign of the infamous Henry VIII, it tells the story of the two Boleyn sisters; one is the famous Anne Boleyn (who became the mother of Queen Elizabeth I) and the other is the lesser known Mary Boleyn. The Other Boleyn Girl is novel about extreme sibling rivalry; Mary Boleyn, already a married lady, was forced by her family to become Henry's mistress in the name of power and privilege. She bore him two children, but after several years, he became tired of her and pursued her sister, Anne, which left Mary no choice but to compete for the affections of the King of England. The book is a marvelous read for those who are fond of historical novels, more specifically the life of the famous Anne Boleyn.
The book's film adaptation, which is directed by Justin Chadwick, stars Eric Bana as Henry, Natalie Portman as Anne and Scarlett Johansson as Mary.