[Your letterhead, if desired; if not, your return address]
[Date of letter—month, day, and year]
[Recipient's first and last names]
[Street or P.O. box address]
[City, State ZIP code]
Dear [recipient's name]:
I am writing to apologize to you for the argument we had during my medical appointment with you on Wednesday. I realize that my tone and words were inappropriate and disrespectful at times, and I very much regret the way I handled things. As you could see, I am quite opinionated regarding the medical issues that we discussed and still stand by many of the views I conveyed. I just realize that the way I said things was inappropriate.
I would like to continue this important medical conversation and would like to see when we can set up a time to talk, either in person or over the phone. I promise that I will be diplomatic and courteous when we talk again. Thank you in advance for your understanding and for accepting my sincere apology. I look forward to setting up a time to talk again soon.
[Sender's first and last names]