I think the dad is just in total denial for his role. It's like, he has a child's attitude.
He brought his horrible woman into his son's life, and ignored that his son's legs were burned to the point that he would die during the night. NO, he did not "get into a bath with his wife". His wife placed him in burning water.
And now he's going on about how you have to forgive, you have to go on, he would want me to keep having fun. No, he would have liked you to rescue him from this witch you brought into the house.
In an aside, I keep posting this in cases like this - why is the household water heater cranked up high enough to burn a child to death? That should be against city code. You do not need tap water heated to the point of burning you to death.
But I don't think the dad is laughing in the 911 call. That sounds like a gag and a sob.