I used to have issues with that somebody (and almost everybody). I kept "it" inside me for a long time. Suddenly, I would go berserk at that somebody. Then, I would hold a grudge.
That was my younger-self.
For instance, I held many grudges to my family, friends, and relatives. (Total count was about 10 people. That hatred.)
I held grudges to prove my enemies a point. I assumed that I was (always) right. I ignored them, until they would come to me for an apology as a loser. I wanted to be the winner.
It never happened anyway. The grudges continued to prolong.
My huge ego took over my mind, body, and spirit. I had a big sense of pride (to the point where everybody is wrong, except me).
For instance, I know a man that hates being told. (Good luck. You can only listen to him.) He will tell you, "You are a philosopher!"
Now, I see long grudges as deadly wounds.
For instance, I am witnessing a long (and maybe never-ending) grudge between blood siblings. They are fighting for their share of land, and they are playing a very dangerous game. (I am not choosing any sides. I visited both sides, and I gave them a hug. I am at peace.) The siblings are going for what they want. Nobody is backing down.
"You do not have any siblings anymore. You have no idea how it is like between siblings." Somebody told me that.
(I cannot be a peacemaker to everybody. That is impossible. It is your choice. It is your life. You cannot force somebody to change.)
Most importantly, my younger-self would never hear the other side of the story, once I held a grudge. (It was always about me.) I realized that I always wanted everybody to completely follow my way, such as my beliefs, values, choices, ideas, habits, and etc.
(I always wanted to go according my way. I was selfish. I was Mr. Right.)
Now, I am aware of it. I am learning from it.
Judging, and criticizing others would extremely boost my self-confidence, and self-esteem.
My younger-self would select my enemies. Once they copied me, such as the way I talked, dressed, and etc, I would be extremely upset. (I chose this "old" happy life. Now, I see this as an "unhealthy" life.)
No winner, no loser. No more competition. No more enemies. No more grudges. No more jealousy.
My past grudges have already been healed, and forgiven. I started these grudges. Thus, I must fix them. I reached out to my (selected) enemies, and I apologized. (My younger-self would think of it as a coward move. Now, I see it as an enlightenment.)
For instance, I was able to reconcile, and come at peace with my tennis, and basketball coach; before he died unexpectedly. I held a 3-year grudge with him. (Imagine if I did not, I would be living a life full of regrets.)
I have accepted his death. Whenever Coach is in my mind, I reminisce the moments we had together.
The natural human power of gratefulness, peacefulness, and forgiveness leads to happiness. (This is my "new" happy life.)
I feel more relieved that ever before.