Expressing your anger is good, it helps to release it. It is a sign of progress that the healthier and cleaner you become the more angry you become. Actually you are not "becoming" more angry, you are just releasing more of that stored up anger until eventually it will all be released. You are doing great and as you can see if you express your anger, it goes away. The problem always comes when we do not express it, then it just sits there and turns into other mental and physical symptoms.
You are doing fine and you are well on the road to recovery.