The Color Purple is taken from the viewpoint of Celie, a woman who is virtually sold into marriage to a man she only refers to as Mister, as she accounts for the next twenty years of her life through her letters. With stepchildren who treat her badly as well as a husband who not only beats her, but takes his mistress into their own house, Celie's family is as dysfunctional as it gets.
I don't know even where to start with the dysfunction because it spans over several different families. I'm almost positive that every family in this book is screwed up somehow. Even the most normal family, the Starks, have the patriarch's bastard son who is hated by his father's wife. From everything to incestuous (adult) twins to a brother who virtually sells his sister into marriage in exchange for an army to everything in between, this book (and its subsequent sequels) has it covered.
So what books can you think of with some messed up families?