講道理......

Ask your LG if he want his son to behavior like him one day. Remember, all children make mistakes as they grow up. It is your job to show them a better way and you can’t do this by screaming and yelling and losing your temper.

Tell him about your fear, print this one out and ask him read:

How to Not Lose Your Temper With Your Kids
http://www.urbandaddies.com/bonding/how-to-not-lose-your-temper-with-your-kids/

He need to realize what he is doing is not good for the kids. Then he can try to learn anger management.