If Jesus got angry, it must be right, because he never sinned. If anger is in our heart already, events will bring it out. This is not a matter of holding it in. It is a matter of starving it but refusing to feed it. Anger always dissipates eventually, so we can just let it happen sooner by not holding on to it and refusing to enjoy it.
People enjoy their anger.
Even though we may feel terrible later, we enjoy the power of anger while we are giving ourselves to it. We get an adrenaline rush and forget all the bad things about ourselves. Every angry person feels righteous. When we are angry we concentrate on the object of it and forget everything else. It is Judgment Day, and we are playing God.