I've read a translation of this book about 10 years ago. The original book is probably English, because it had English names as I recall. I'm not very good with remembering the names. The language of the book I read was in Sinhala. I'm sorry but I don't know the year that the original book came out.
A teenage girl moves into a new home in a coastal village with her family. She's adopted and her adopted mother is pregnant at the time when the story starts.
The teenager finds a mysterious doll in the new home. She gives it a name, I think it begins with A (Amelia, maybe. Not sure). The doll starts talking to her and making her do things. It's revealed the doll is controlled by the evil spirit of a dead girl who died years ago. The teenager gets more and more infatuated with the doll and kills one or two kids from the village who are mean to her (it's unclear who actually carries out the kills: she or the spirit).
At the end, the girl commits suicide. The epilogue shows her newborn younger sister discovering the same doll and gives it her dead older sister's name.