I have been working with your kind office for the better part of my working years and I know you can vouch for my professionalism and work attitude. But there was an incident which happened recently which I feel may have tarnished my good image and reputation to you.
In this regard, I want to convey my sincerest apology to you. I know that the incident may have offended some sensibilities, yours especially, and I wish to tell you that it was not intentional. I am writing this letter as a sign of my good intention.
However, if this apology is not enough, I am ready to face the consequences of my action. I will also resign my position if my continued presence in my office is already tarnishing the reputation and good standing of the company.