I don't see any grief either. And that is one of the main reasons I don't believe his version of the story.
He said that he saw SW strangling the baby, and in a fit of rage, he strangled her, killing his unborn child. How grief stricken would a man be, to see his 2 girls strangled to death, and then to be forced to kill his unborn son nd his wife?
But the next day, we see a nervous jumpy, but smiley man, who made small talk about his favorite shirt. Not a broken, grief stricken man, like we saw when SW's father spoke.