Pray for your enemy.
I recently had a friend share how hard it is to forgive sometimes. The offense was certainly painful.  Not one to easily get over.  As I shared the account with the Lord,He shed new light with me. 
When I encounter an offense from you  — particularly if you are someone who has not realized that the Lord has reconciled us to Himself, I feel hurt, wounded.  It is especially painful if I you are someone I love.
My first reaction is to become angry with you. I want to rail at you and let you know how wrong you are and what you did hurt me.  I want you to admit your wrong and believe that will make me feel better. I want justice.But it doesn’t come.  And  when I demand justice from you or the Lord, I forget one very fundamental truth.  Christ has already done that for you and me, two thousand years ago.
I will only realize and feel better as i embrace my own justification from our Lord and share it with you.  As share with the Lord  what you have done and look at you, I begin to see what He sees and strangely I start to feel better about me.  My hurt diminishes. I am healed!
Now I can see the Love the Lord has and is for you an me.  II am healed and have new life
Forgive as you are forgiven.  You will feel better.