[Your Name, & Address here]
[Recipient Name & address here]
This is just a short sorry note to you.
I am really ashamed of myself for my behavior with you the other day. I have realized now that I insulted you a lot. I am heartily sorry for that incident. I know that you never expected this of me, and it should be hard for you to forgive me for such behavior of mine.
But, I want to tell you that I really didn’t know what was going in my mind when I was arguing with you. I didn’t listen to you and shouted on you many times. Had I listened patiently to you for once, everything would have been clear between you & me.
My behavior was totally insensitive & unacceptable.
Please forgive me for what I did. I really never meant it by my heart. I am not feeling good since the day I fought with you and feeling guilty inside. I am in huge embarrassment because of this incident.
I am really sorry. I want to make it up to you.
I am deeply sorry.