It's ok to express your emotions but don't let them lead you. Because you're not your emotion. The emotion belongs to you but it doesn't make you. There is difference between saying "I feel anger in me" which means "I'm angry". The next step would be "I'm the anger". If we say "I'm the master of my emotion" that is good. But to be the slave of your emotion is not good. And that is what happens if the emotion drives you. If the emotion takes over, you are the slave of your emotion not the master.