I stop, breathe deeply and evenly and open to my pain . and then relax into it. Then my mind steps in and I start "talking" logic and sense to my pain, and try to see things from other points of view, and work on generating compassion both for my pain and for the other person whose unhappiness has caused their behavior.
After a while, you get good at this and it happens very quickly. But you have to remain aware most of the time, so you can CATCH your anger BEFORE it turns into a tidal wave that washes over you. This awareness has to become a constant thing (it is not the same as hypervigilance, since this kind of awareness is relaxed and accepting rather than fearful and tense).
Anger is pain we don't want to face. Because we are afraid to face it, we convert it into anger is stronger than pain .. and then we have to blame someone for how we feel.