Anger is a normal human emotion. It can let us know when something is unjust, or we have been hurt. The trick is not to dwell on the hurt, but to address the cause with love.
Father of Mercy,
you are slow to anger and abounding in steadfast love.
Remove not my anger, but let my love be stronger.
Let my heart have anger for injustice,
but more so, may I have love for restoring the justice that was lost.
May your loving kindness restore what has been wounded.
Identify a place where you have been harboring anger. Ask the Lord to reveal the source of it, and also to reveal a loving way to respond.