Wicked Games by Ellen Hart

When Jane Lawless rents her quaint third-story apartment to a new tenant, children's book author Elliot Beauman, she unwittingly opens the door to a sinister, decades-old mystery that has been waiting patiently to unfold--in her own house. Meanwhile, Jane assists a detective in tracking down clues about her new neighbor, Patricia, whose husband died mysteriously. Patricia is eager to become friends, or more...even though she knows Jane is immersed in a long-distance relationship with the attractive but secretive Dr. Julia Martinsen. Little does Jane know that a strange man upstairs, an attractive neighbor, and a volatile love affair, are just the beginning of her problems.