Rain, by the way, I was a recruiter and career counselor for a few years and had my own business. I am more concerned about your getting a bad reputation by handling the situation poorly (and this reputation will follow you throughout your lifetime) than in you losing this job. Please remember to maintain your dignity when you write this letter. Everything that a person puts in black and white comes back to haunt them in the future and speaks volumes about a person as an employer and a human being. Like I said, if you need help, I am here for you.