How to write an apology letter after a fight? To each other's parents.

On X, X, X, I quarreled with your son because of XX, and finally I slapped him because I was too impulsive! I regretted hitting him, but I didn't apologize because I wanted to save face. He was very angry when I hit him. He just punched me. I didn't want to suffer, so I kicked him a few more feet, so we started fighting.

Later, the students came to stop the fight and stopped us. This is the end. Afterwards, I regretted it. I want to apologize, but I don't know how to make you forgive me. Finally, I decided to write an apology letter to express my apologies. Uncle, I was wrong. I feel sorry for you. Now, I'm not asking for anything. I just hope you can forgive me. That's enough.