Some Girls Are, by Courtney SummersRead about another entry on the list.
Regina used to be one of the mean, popular girls, until the HBIC and her former BFF, Anna, exiled her. Now she’s not exactly popular, but she’s sure as hell still mean. Becoming friends with one of her former victims seems to be softening her edges, but it’s hard to make up for putting a guy through hell, as Regina herself is learning firsthand. Besides, getting close to someone just means giving the girls who’ve turned on her another tool for torturing both of them.
Some Girls Are is also on Adler's list of five YA books told from the bully’s perspective.
The Page 69 Test: Some Girls Are.