I am very familiar with this situation. I wish people cared more for their children than they are upset with their ex's. The children suffer so much.

I catch myself doing this, it's built into culture in some regards. The ex wife jokes as a for instance. I also see this sort of harm to children being done through media. It is normalized.

Teaching people to be decent towards their baby's other parent shouldn't be mandatory class, but at this point it seems genuinely needed.