Proverbs 29:11 A fool uttereth all his mind: but a wise man keepeth it in till afterwards.
Feeling anger is not a sin, however it is particularly dangerous. Anger stirs other emotions and also stirs our selfishness and pride. It is just one emotion that has the potential to deceive our hearts, and ultimately damage not only our lives, but the lives of others close to us.
We experience a great spectrum of emotions throughout our lives. Allow the Holy Spirit to help you through what is going on, and hold responses until His counsel comes. His advice will lead you to a right response, at the right time. Trust in His leading.