Mind of a Stranger — Ruth J. Hartman

Shelby Wright has the life she's always wanted: a loving marriage to Charlie, her best friend, companion, and lover. She can't imagine anything ever coming between them. They're so close, nothing ever could. But when Shelby's mind begins to play tricks on her, little annoyances grow. She's plagued with doubts when she can't remember whether she's done something. A voice in her head plants an unease that she can't ignore. Then at her job, everyday occurrences that never bothered her before seem larger than life. Suddenly, life is more than she can handle. What's happening to her? When her thoughts take a dangerous turn, she's scared out of her wits. And she can't tell Charlie because the woman he promised to love, honor, and cherish has been overtaken by a monster Shelby can't control.