A business owner, who we also call, a boss is not a king, so there is no reason why feel afraid if commits a mistake. You just need an explanation. In the busenss center, one mistake would be the services for the customers which might not be satisfactory as shown in the feedback. Saying the word sorry is easy to say and promise not to make the same mistake again. We have to value our customers, so should not show them our arrogance no matter how tired are we at work. They also deserved respect. A boss could understand your case and may give you a second chance.