You are exhibiting bipolar tendencies.
I used to have this problem. I sought counseling and medication, and in the end all that saved me was the development of a coping mechanism.
When I get angry, I imagine the ocean. I think about it until I can hear the waves crashing and nothing else. I listen to the waves until I am no longer angry.
Then I examine what made me so angry, and if it is a silly reason, I resolve to abandon the anger the next time it comes up.
This requires diligence and perseverance and no small about of very hard work. It will not always work, but you have to keep trying.
The first step was asking for help. Everything else will come if you keep asking for help, and be as patient with your self as you are asking others to be.