Why do you automatically assume he is a jerk? Do you know more about his personal life than what was mentioned here? How do we know she wasn't a horrible person and this is actually a gracious response?
I really have no idea, but I think it's pretty unfair to make character judgements from a single note out of context. Human relationships are complex.
The OP is making a judgement based on the evidence he has, not on the evidence he doesn't. You on the other hand are attempting to counter his argument with no evidence at all.
If you want to counter the argument, present contrary evidence.
He wanted to remain together just for the children. It's pretty safe to conclude he would not have done so if he had no children and that her presence is detrimental to him in some fashion. The terms listed are harsh, but they reflect his priorities quite well. Calling him a jerk is a bit out of line when he's prioritizing his children highly enough to try being a father when that isn't his most important goal.
What a horrible way to argue. So the thought "the evidence might not be sufficient" never comes to your mind? Uncritical thinking like this ("knee jerk reactions") are one of the banes of humanity.
I really have no idea, but I think it's pretty unfair to make character judgements from a single note out of context. Human relationships are complex.