Personally, I think he has NO IDEA the burden and the toll it will take on his marriage...
Every time he looks at his wife with love in his eyes, makes love to her, shares a tender moment, hugs his kid...
In the back of his heart will be the thought....she killed my children and I was a coward to stop her...
He will need God more than ever to survive the pain...
You pretty much summed it up. He wanted to increase and multiply but his wife was too gutless and self involved to do this. So now she will regret and suffer for decades and him too. This is very very bad stuff and this is why he posted as anonymous.
My summation— his wife is a mad beast. She was conflicted about the decision but her inner beast (call it dark forces) won out