The Impossible Knife of Memory by Laurie Halse Anderson
While this story shows the real side of PTSD from a war veteran's perspective, it really follows the effect this disorder has on the family as they try to deal with this together.
From the Amazon summary:
For the past five years, Hayley Kincaid 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. Will being back home help Andy’s PTSD, or will his terrible memories drag him to the edge of hell, and drugs push him over? The Impossible Knife of Memory is Laurie Halse Anderson at her finest: compelling, surprising, and impossible to put down.