I think it’s more simple than people think.
In spite of efforts to paint men as cold and emotionless brutes who only lust after sex and power, often the family is the only thing in this world that gives men purpose. In fact, many wives are far more religious than their husbands. We may have invented religion but we don’t see it the same way, typically.
So a man who has invested everything he is into his marriage might, when facing the loss of such, go to places he would never have planned to before.
But let me also add that some people are abusive narcissists and when faced with the prospect of losing control react violently.
But often we don’t hear enough of the details to know which is which in these cases.
But it is evil for a man to kill his children too, no matter the anger he feels towards his ex (and yes, it’s wrong for him to kill the ex also, no matter his grievance.)
Just another mental breakdown. There are 5,000 per day throughout the US...with at least a dozen involving a murder.