Can anyone help name this Young Adult novel for me?
- published no later than 1995
- cover I saw has a young woman's face with a line down the middle and the two halves looking different (but clearly the same person)
- basic story: young woman (YW) is unhappy with her family life, and one day she meets an older woman (OW) who has lost her daughter. The YW looks a lot like the OW's dead daughter, so the OW (who is wealthy) starts inviting her over, giving her clothes to wear etc., and they become close. However, over time, the OW becomes delusional and has convinced herself that the YW is actually her daughter. If I recall correctly, the book ends
I have googled repeatedly and also looked at popular YA lit lists and still come up with nothing, so this is a long shot I guess. Thanks in advance for any suggestions.