Fear, anxiety and anger are relatives. In my mind, they look like brothers. I don't know which one is the older brother and which one is the younger but I am sure they are related and so is psychology.
When you get anxious (it is not fear but something similar to fear, information for those of you aliens out there who haven't had an experience of anxiety), there are sure reasons. Those reasons are most probably the ones that would make you angry. Somehow, anger gets opressed and turns into fear or anxiety.
Anxiety can be so strong - like it is in panic attacks - that you cannot keep your mind together at the moment and can't think logically. If you could, I am sure you would find out that you are angry towards something or somebody.
Anger is better than anxiety because anger serves a purpose, it is functional. If not excessive, it will lead you to proper behavior and make you out of the situation that gives you anger. However, anxiety's only function may be considered as a warning to you. Other functions of anxiety is making you sick all over.
We live in a society somehow. We are not alone. We have roommates, neighbors, colleagues etc. that we have to get along with. Now, in this community type of life, conflicts emerge. At this time, you have to be assertive to explain your arguments. A certain amount of anger will help you to be assertive enough. Anxiety will do the opposite. Moreover, anxiety will lead you to depression if it becomes persistent.
So, work on yourself, study yourself and find your fears and aggressions. Then control them. This may be a long process. If it takes to long to no availability, consider consulting talk therapy. It would help you understand yourself faster.