You shouldn't disown your seed for ANY reason. If his marriage is over, it's over no matter what he does with the kid. The wife is obviously hurt and wants others to suffer with her. If he disowns the kid it's not gonna magically make her hurt go away. He already fukked up and probably isn't too thrilled with his married life anyway(hence the cheating) so he might as well do the right thing and take that L. Hopefully he wont make the same mistake again.