Question: I am aware of the danger of losing ones temper and I try my best to avoid doing so. But I find it difficult to discipline my children when they get out of hand without demonstrating how upset I am with their behavior. What is the right thing to do?
Answer: Your dilemma has already been dealt with by our Talmudic Sages (Mesechta Shabbat 105b).
Rabbi Yochanan ben Nuri is quoted as comparing one who breaks things or disposes of his money in anger to an idol worshipper. (A classic example of such behavior was recently provided in Israel by a man who became so incensed with a member of his family that he took three million shekels of the family savings and set them afire.) If the purpose of such a demonstration of anger is to impress upon the members of ones household how strongly he objects to their behavior, it is permissible to even do some nominal breakage.
Rabbi Moshe Chaim Luzzatto, in his classic Mesillat Yesharim, points out that even while the Sages mentioned in the gemara were demonstrating their anger, it was only a show, for in their hearts there was no anger. This should be the guideline for you in disciplining your children. Learn to show anger but make sure that you are calm inside because real anger can cause you to lose control and act in a counterproductive way.