What does Frank think about as he leaves his farm after finding Marie and Emil together?

As Frank rides to the train station, he has a terrible pang of conscience over the suffering woman he left behind. Then he gets angry at Marie, who probably cheated on him many times before this one. He always wanted her to be as unhappy as he was, but had not succeeded. She had brought this tragedy on herself. As he nears Hanover, he gets physically sick. He longs to be comforted by his wife.