Into the Darkest Corner - Elizabeth Haynes
This book is written it two parts, telling a story of a woman slipping into her darkest corner.

Catherine's relationship with Lee is great until his true self begins to come out. He is controlling and abusive and thinks he is charming enough to manipulate the people around Catherine.

Four years later, Cathy is suffering from obsessive compulsive disorder and post traumatic stress, and trying to get her life back on track.