Grounded: The Seven, book 1

Hannah Rose was able to convince herself that she was a normal teenager, even though she usually knew exactly what was about to happen next. Until one day when she set her jerk of an ex-boyfriend on fire-from 15 feet away-propelling herself into a world of weirdness.

Rosie is sent to live with her aunt in Brooklyn. There, Rosie discovers a family legacy of strange abilities and dangerous talents. Her training tests her gifts-and her patience-but over the summer she does begin to learn to control her unique skills and meets a boy with equally dangerous strengths. Together, they find a sort of peace that neither has ever experienced, and it looks like it will last-until disaster breaks them apart in a way neither saw coming.