[ she may have been done, but after all she said, he... needed closure, but he didn't dodge her attack. He didn't lean away her slap. He turned into it, taking the full force as his just due.
He could do no less.
But he still didn't feel right, letting her walk away. He saw that look; he knew what it meant. Hurt, frustration, resignation. The anger was better, cleaner. There was nothing else to be done but let her go. He's made his bed; he will lie in it.