Anger gets a bit of a bad rap. People talk about anger as though we should never feel it and we certainly should never act on it. Neither of those are true. There are times when it’s not only reasonable to feel angry, it’s right to feel angry. If you’ve been wronged, treated unfairly, or provoked, you should get angry. In fact, would worry more about someone who didn’t feel angry in those circumstances.
That said, we all know that anger can get out of hand. How you handle it is different from whether or not you feel it. Again, it’s ok to act on anger too. It’s just that, usually, it’s best to be polite, assertive rather than aggressive, and calm when you act on it.