Why do I lose my footing when a patient's family gets angry?

You can carry a full patient load without blinking now, real competence, hard won. But the second a family member turns their anger on you, the floor drops out and you lose your footing. That is not a weakness in your nursing. It is a specific, human tender spot, and almost everyone has one. Understand what is actually happening. A frightened, angry family member is not really attacking your skill. They are scared for someone they love and pouring it onto the person in front of them, which is you. Their anger is fear wearing a hard face. When you can see it as their pain instead of your failure, it stops knocking you over quite so easily. Give yourself a small, steady move for those moments. Take one breath before you respond. Let them be upset without deciding it means you did wrong. Say something simple and human, that you can see they are scared and you are there to help. You will not stop caring what people think of you, and you should not. But you can learn to stay standing while a scared family lets off steam. That footing comes with practice, not with never being rattled again.