Dear ______________,
I would first like to say that I am sorry that I _______________. I did this because ____________, but that does not make my behavior acceptable. I know that this was inappropriate because __________________. I would like to make amends for what I did. I would like to make it up to you by ___________________, but if something else would be more appropriate, please let me know.
Again, I am very sorry that I ________________.
Sincerely,