The book of Otto and Liam / Paul Griner.

Enhanced descriptions from Syndetics:

Liam is the boy, lying in the hospital, in grave condition, a bullet lodged in his head. Otto is his father, a commercial artist whose marriage has collapsed in the wake of the disaster. Paul Griner's brave novel taps directly into the vein of a uniquely American tragedy: the school shooting. We know these grotesque and sorrowful events too well. Thankfully, the characters in this drama are finely drawn human beings--those who gain our empathy, those who commit the unspeakable acts, and those conspiracy fanatics who launch a concerted campaign to convince the world that the shooting was a hoax. The Book of Otto and Liam is a suspenseful, edge-of-your-seat read and, at the same time, it is a meditation on the forms evil can take, from the irredeemable act of the shooter himself, to the anger and devastation it causes in the victims' families. Griner has managed to make an amazing, incredibly powerful book, one that is like no other.