The Impossible Knife of Memory by Laurie Halse Anderson

For the past five years, Hayley Kincain and her father, Andy, have been on the road, never staying long in one place as he struggles to escape the demons that have tortured him since his return from Iraq. Now they are back in the town where he grew up so Hayley can attend school. Perhaps, for the first time, Hayley can have a normal life, put aside her own painful memories, even have a relationship with Finn, the hot guy who obviously likes her but is hiding secrets of his own.