If you let the enemy into your house, he will take up residence.  

“Be angry, and do not sin”: do not let the sun go down on your wrath, nor give place to the devil.” Ephesians 4:27

Anger is not a sin. However, when we act upon it, we get into trouble.

“So the Lord said to Cain, “Why are you angry? And why has your countenance fallen? If you do well, will you not be accepted? And if you do not do well, sin lies at the door. And its desire is for you, but you should rule over it.” Genesis 4:6-7

Cain chose not to listen to the Lord and allowed the anger to take root, and the sin that resulted was murder.  

You can rule over the anger. First and foremost, forgive the person that has hurt you, then get rid of any resentment and bitterness.

Lord, I ask that you heal the hearts of those that have been hurt deeply. Cause them to know your love. Help them to forgive and give everything to you, Lord. I pray this in Jesus’ name.