I have made a very grave mistake that could cost me my job. I am to present myself before a disciplinary hearing to hear judgement on the matter. I would like to write a sincere letter of apology and strongly plead with the institution any acceptance that this would be my last opportunity to redeem my self and retain my job if they show mercy. Please help me to write this letter. Here is what I have so far. Dear Disciplinary Panel,
I am writing to express my sincere regret for my recent utterances to a member of staff that is deemed as sexual harassment. I understand that my behaviour was inappropriate and unacceptable, and I deeply apologize for any harm that I may have caused.
I have never intended to make anyone feel uncomfortable or unsafe, and I am truly sorry that my words have had this effect. I want to assure you that I have no intention of repeating this behaviour in the future. I have learned from my mistake, and I am committed to being a more respectful and considerate person.
I would like to ask for your forgiveness and leniency. I value my job and I am committed to my work at this school. I promise to be more mindful of my words and actions in the future.
Unfortunately, my background in the building trade, where it is customary for builders to talk recklessly, has affected my judgement. I have never had colleagues, employers, nor siblings, friends, children or a partner who could have corrected or enlightened me of my incorrect behaviour. I am also well into my 50s, still single and have not been accustomed to the ethics of appropriate communication. 
I am aware that my actions could potentially cost me my job but I plead with the institution to extend me a last and final opportunity to show that I am committed to making changes in how I interact and communicate with others from now on.
I am truly sorry for my actions, and I hope that you will consider my request for forgiveness and leniency.
Thank you for your time and consideration.
Sincerely,

<PRESIDIO_ANONYMIZED_PERSON>
