Summer Heat by Rachel VanDyken

This is the first installment in a series called Cruel Summer that will prove to be a favorite! In Summer Heat, you meet Marlo and Ray, enemies since forever, thrown together as staff in a summer drama camp. True enemies they are not-just warring should be loves. His rage at her maltreatment of him in high school boils over but the love he has for her takes control. He sees her as a favored princess but in reality her life was hell.
I cannot wait for the next installment!