why should i let go?

One of my brothers who speaks so straightforwardly irritates me sometimes.
Three days ago, I called him and asked how he was doing. He complained about there was a big mistake made by his stuff that he needed to fix the problem. And I told him that it should be fine and the event will be fixed. You know what he replied to me angrily?
"It is not you who take care of this crisis. It is ME!"
Ya! Sure! Even it was not my business but i was worry about him as well. With a very bad mood, i hung up the phone! I called him because of my goodwill. Just wanting to spread some joyful aroma to him.
All right, the task was coming . Since i am a christian, i know the God's rule which i need to forgive the one who transgresses against me. But i didn't want to. Why?
Number one, i did nothing wrong. Number two, i cared about that brother so i called him to see how good he was. I AM TOTALLY RIGHT!! And besides, he gave me such bad attitude so many times.
So for entire two days, i tried to ignore and forget the rule.
You know once there is a rebellion against God, there is no conversation with Him. Not a word!
Even though the rule turned off the channel with God, i still felt i am reasonable.
This morning, as usual, i prayed to God. I saw that i was just like a child holding small rocks so tightly . I started crying. I knew what God wanted to tell me.
I was willing to forgive that brother and i prayed. I saw my hands opening and the rocks dropped.
There were two meanings for the rocks: one was the authority of accusing that brother and another was a trash in God's eyes.
I was willing to give up the accusation of that brother. Suddenly, the burden dropped and the joy and new relation with God came back!
Praise the Lord! I am free again!