fiction, womans has affair, , living with man who tried to kill her

woman has affair, the man tries to kill her, she looses her memory. She is put in a home for those with mental problems and then brought home by a man she is told is her husband. Every day she wakes up and does not remember anything....she must be told her name, her routine, etc.
She finds out the man who says is her husband is not her husband- they had been having an affair and when she tried to break it off, he tried to kill her.

Before I Go To Sleep by S. J. Watson? It was made into a movie with Nicole Kidman and Colin Firth.