Controlling facial muscles can help control your anger. Studies have shown that if you don't frown when you are angry, you won't feel the emotion in much intensity.
Arguing over text is the worst way to argue because the lack of tone decreases the meaning of the words. Talk it out in person.
Not only do most people enjoy humor, but it breaks the attention and stress caused by feeling angry and refocuses it on something less physiologically taxing.
One thing that has been shown to consistently combat anger is humor.