Help finding book title!!!

[Jessica]

I read a book.. probably 17 or 18 years ago. It was a young adult book..I'm trying to remember who wrote it and what the title is as it was such a powerful book back in the day.

Premise was basically girl (A) and her boyfriend were madly in love. another girl (B) who is mentally unstable becomes obsessed with girl (A) takes her captive. Girl (A) plays along and pretends to be in love with Girl (B) but is trying to kill her before she gets killed. Boyfriend shows up. Girl (B) makes girl (A) shoot her boyfriend to show that she really is in love. Girl (A) shoots her boyfriend.. thinks she kills him and then turns on Girl (B) and kills her. Then it pans in to the future and Girl (A) sees her boyfriend stumbling towards her, he is alive and the bullet actually got stuck in a necklace she had bought him.

any leads please help!!! this has been bothering me for years!!!

[Ayshe]

You need to post that in the What's The Name of That Book??? group, not as discussion for Beowulf :)