Anger causes an extreme display of emotions. Sometimes we justify our anger. We feel we have the right to be angry at someone or something. That righteous anger is a violation of God's moral law and can always be self-controlled.
We need to face up to our anger and realize that no one else is causing us to be angry. Being angry is a choice. Our pride is a huge cause of our anger along with selfishness and our desire to control.
If we are mistreated, we need to respond by being mindful to God. Start by asking yourself these questions with situations arise:
How would God have me respond in this situation?
How can I best glorify God by my response?
Do I believe that this difficult situation or this unjust treatment is under the sovereign control of God and that in His infinite wisdom and goodness He is using these difficult circumstances to conform me more to the likeness of Christ?
We need to develop this new habit of reflecting on such questions in a heated situation instead of holding onto our anger. Daily, we come into contact with circumstances or actions of other people that tempt us to be angry. But they never cause us to be angry. The cause will always lie within our prideful and selfish hearts.
Handling our angry starts with recognizing and acknowledging the anger we possess and how sinful it is.  Paul tells us in Ephesians 4:32 to "Be kind to one another, tenderhearted, forgiving one another, as God in Christ forgave you." He always writes "...bearing with one another and, if one has a complaint against another, forgiving each other; as the Lord has forgiven you, so you must also forgive." (Colossians 3:13)
Remember no anger is justified and acceptable to God.  Let's take the first step today recognizing our prideful hearts and forgiving those people and things that made us bitter.