Anger is my primary reaction emotion. I think it is for a lot of men, since society doesn't support men having other emotions. When I get frustrated, I get angry, particularly as a caregiver, when I see things not moving smoothly for my wife.
This is what I do. First, I blow off a little steam often, so it doesn't build up -- I verbalize my frustration to someone supportive or to the air. It helps me get over it just to talk about it, as you have here. Second, I look back at the events in the coolness of time and see how I could react better, get things going more smoothly -- I have found it I am insistent (assertive) without getting all angry and emotional, I get more things done through others. I try to remember that. I don't back down -- I just try to remain calm and creative and assertive. Third, I have a few selected people I talk with on a regular basis to vent my "ain't it awfuls".
As an example, my wife takes morphine for pain. The druggist we go to has had trouble supplying the med in a timely fashion. At first, I ranted and raved, and eventually got things done, but it was hard on everyone, including me. Lately, I have tried the calm, assertive approach, and the druggist has actually called around and located the med locally for us when he couldn't get it right away. Now we are friends and I see him as an ally instead of the enemy.
Works for me. And it is better for me and those around me. Not an easy task, but one worth working at. Good luck. Don