When you are calm, it's easier to see the emotional pain of others. That is when you can build up your attribute of compassion. The goal is to have so much compassion that even when you personally are experiencing emotional pain, you are able to be sensitive to the emotional pain of the person with whom you are interacting.
Coming from a place of compassion you will be able to address the thoughts and feelings of the other person in a way that alleviates his distress. Then he is more likely to speak and act more sensibly and reasonably towards you.
(from Rabbi Zelig Pliskin's book: Harmony with Others, p.130, artscroll.com)