Before I Say Goodbye by Mary Higgins Clark

When architect Adam Cauliff’s cabin cruiser explodes in New York Harbor, his wife Nell MacDermott is left grieving—and haunted by a cruel final quarrel. As the investigation turns from accident to bomb, Nell discovers the deadly real-estate deal Adam had secretly entered and is drawn into a realm of psychic whispers after a medium claims Adam’s spirit is reaching out. Pushed into extremes of suspicion and revelation, Nell must unravel the web of betrayal before the same hand that destroyed Adam ends her chance at truth.