Lasher (Lives of the Mayfair Witches) by Rice, Anne (1994) Paperback

The novel begins shortly after the mysterious disappearance of Dr. Rowan Mayfair, recently married to contractor Michael Curry. Michael, feeling betrayed by Rowan, has sunk into a depression helped along by the useless drugs prescribed to him after his close encounter with death. Along comes the sexually adventurous Mona Mayfair, a precocious teenager and powerful witch and Rowan's cousin sharing lines of descent from Julien. She seduces Michael, causing him to snap out of his stupor and renew his vow to find his wife at all costs.