The trick is not to control anger, it is to bypass that emotional response entirely. I discovered a method for retraining my unconscious brain to do that in an obscure self-help book. It took 2 weeks of intensive focus, but it worked. I went from getting angry every other day to getting angry on average about once a year.
Since the book that I got this from has gone out of print I intend to write a short ebook to spell out the details about how this process worked for me and how I used it to improve several areas of my life. In the meantime, here is a short reddit post
https://www.reddit.com/r/poker/comme..._tilt/c9udmhf/ where I summarize the process.