Mindfulness techniques could help. Instead of trying to actively calm yourself or fight the anger, just try to take a step back and let the feelings flow through you, observing them as if they are something you have no control over like the clouds outside your window or the weather. That way you'll realize that they pass naturally and don't control you any more than you control them.

Another good thing about that technique is that by fully being in the moment and looking all those horrible thoughts and feelings in the eye, we can become more reflective and stop putting hurdles in our way and that's when the real change takes place. People who don't change are often the ones who push away the angry feelings or pretend they're not there.

I wish it was that simple in reality but it all seems to work in theory and sometimes... I manage to put it into practice