The Spy Who Totally Had A Crush On Me — Michael P. Spradlin

With a traitor in her midst, Rachel faces losing her life and her heart -- all in one semester
At Blackthorn Academy, a peculiar prep school in the mountains of Pennsylvania, students are concerned with all the usual things: homework, hookups, and how to save the world. For Rachel, studying has taken a backseat to a little problem she's having with a supervillain named Simon Blankenship, who is convinced that he's an ancient Roman god and she's a reincarnated goddess whom he must destroy. They've tangled twice before, and Rachel has beaten him narrowly both times, but now Blankenship has done something completely unexpected: He's stolen an important ancient artifact from Blackthorn Academy . . . and disappeared.
She and her fellow spies in training wait for Blankenship to show himself while contemplating the possibility of a turncoat in their midst. And as if that weren't enough, Rachel must tangle with a different kind of problem: a totally cute new student, whose eyes are just a little too pretty, and who seems to know just a little too much about Rachel and her past. She must decide quickly -- is he boyfriend material, or a traitor?