"The Reader" book tracks all the main characters and general plot pretty closely, but the book paints the guy as much more of a jerk than the film.
In the novel, the guy spent the rest of his life hiring prostitutes to imitate his memory of Hanna putting on her stockings. The film shows Hanna putting on her stockings, but never refers to it again.
In the novel, the guy goes to speak to the judge to explain that Hanna was innocent of writing the report because she couldn't write, but when he meets the judge they just engage in small talk and he never says anything about Hanna's illiteracy. And that pretty much condemns her.
Also in the book, he had lots of sexual fantasies about Hanna as a sadistic SS guard.
So the guy was actually a pervserse twit, but in the film he's portrayed as normal.