Behind Her Eyes by Sarah Pinborough

David is a psychiatrist who is given Louise as his new secretary but his first day of work is not their first meeting and soon Louise is caught between her boss and his perfect wife. The perfect wife, Adele, has also met Louise and struck up a friendship. Louise thinks she is losing her son to her ex-wife and new family and is ripe for the taking. Things heat up quickly with this strange little threesome and they are soon immersed in problems, games, trust issues and questions of abuse.
But just who is the abuser and who is the abused. This book messes with your head and you enjoy it up to the very last page and ending you won't see coming. Warning - you may start to look twice at your boss and friends.