Dear {Recipient},
In light of our recent professional disagreement, I would like to offer you an apology. Sometimes, colleagues find that they disagree, and while I believe neither of us was truly wrong about {dispute}, my behavior during our disagreement was unacceptable.
I should not have resorted to unprofessional language, and I certainly should not have said {statement}. As adults and professionals, this is not the way I usually act. I value you as a colleague, and I hope we can discuss this issue like adults in the future.
I think it would be appropriate for us to talk this out over dinner at your favorite restaurant, {restaurant}, or at another venue of your choosing. I would love to take you out for a meal and really get this out of our systems so we can go back to our former cordial relationship. Let's schedule a date that's good for you soon. And, again, please accept my most humble apologies.
Your friend,
{Sender}
