Diary of the Fall by Michel Laub

The book at Amazon and on Kindle

A cruel schoolboy prank leaves the only Catholic boy in an elite Jewish school in Porto Alegre terribly injured. Years later, one of his classmates revisits that episode, trying to come to terms with the choices he made then and his present demons.

Diary of the Fall is the story of three generations: a man’s struggle for forgiveness; a father with Alzheimer’s, for whom recording every memory has become an obsession; and a grandfather who survived Auschwitz, filling notebook after notebook with the false memories of someone desperate to forget.

Source: Jewish Book Council