Anger is an important part of the path when you are both healing emotionally and growing spiritually. If you refuse to express your anger because you have some belief, known or unknown, that it is not spiritual to have anger, or sometimes in the case of women that it is not appropriate for you to be angry, then anger that is repressed will become depression. So anger is important, but this does not give us carte blanche to tell everyone to stick it. You come to a point in your path with God when you realize that the last thing you want to do is hurt someone else's feelings. Cause and effect do not appear to us to be instantaneous, but they are, as this was how Jesus performed miracles. So we do not see the effects of our actions and thoughts and how instantaneously this creates a ripple effect to everyone around us and especially the person we are getting angry with. If we could see how powerful and strong our words and thoughts are, there would be much less anger and hurting of feelings. Additionally, if we could see from a perspective of the One, then we would realize that our harmful thoughts and words are only hurting ourself.
If you are growing in your remembrance back toward God, there will be times that you get angry with Him. You are working through and releasing false beliefs about your relationship with Him and your ego does not give up its influence easily. Many people do not think they can get angry with God because they fear Him and His punishment if they get angry. But God is Love. He loves you regardless of what you do, what you are, what you think, etc. He is not a human parent who has conditions on his love. Unconditional means there are no conditions to earn His Love. It is there, no matter what happens, eternally.
So how do we balance the fact that we need to be able to express our anger with the fact that we don't want to hurt feelings. Well, certainly with God you do not have to worry about hurting His feelings. You can let it go full blast --- He wants this as there is less of the false you there to block His Love. But in regard to anger at other people, it is a balancing act. If you can catch yourself becoming angry, ask yourself whether it is more important to blast the other person, hurting their feelings, or is it more important for you to express your anger in a less hurtful way. You can find out a lot about yourself and how far you have come by the internal response you get. As we do in many instances, we look to Jesus as an example. Jesus became angry at the moneychangers in the temple. But I strongly believe that his anger came from Love. His words and tone were such that in this instance, he taught the truth through anger, but it was done in a completely non hurtful manner. Because he knew himself as one with All that is, he would have never hurt others as he would have only been hurting himself. Anger happened to be the best vehicle for making these people understand what they were doing. The Love he had for these people (because he was nothing but Love, having recognized himself as one with God) was expressed through anger. In most other times he expressed Love through "love". Love can be expressed by being sad, being kind, being angry, etc. Love does not look a certain way. It has many appearances in this world, but they are all Love, as there can be nothing else.