What should I do about my brother in law?

My wife and I are staying with the in laws for Christmas and it is the first time I have met her brother in law. I have heard stories but I was still suprised about this man's behaviour. He and my my wife's sister have two ypung children (6 and 1). He practically ignores them except to shout obscenities at the eldest for being too loud/ messy/ an annoying little shit [sic].The other is ignored to the point where she can be screaming for minutes until the mother can come and deal with baby. When me or my wife approach the baby we are angrily told "No. That is HER job." (meaning his wife). He is a gamer and any moment he is in the house is spent playing war games at full volume. He says he has to "do this to drown out the shit." A few days ago I was helping the eldest with some school work. We were sat together looking over a textbook when he passed by. "I don't know why you are bothering with her. IT'S TOO FUCKING STUPID TO LEARN ANYTHING! It never listens to a word anyone says. Just a waste of your time!" he said.Why is the wife with him? My wife's family have old school values of sticking with your partner no matter what. Etiquette says not to question a man's behaviour in his own house but this is absurd. I also know that he will get very angry and defensive. I imagine being thrown out of the house in one of his rages if I do speak up. I have so far taken the approach of showing him what a father should be but this doesn't seem to work because he just yells at the children to shut up when we play together and tells me they are too young to play outside. via /r/Parenting http://ift.tt/2DHzMvo