Like I said it was my first time and a huge mistake!!
No, it wasn't a mistake.
Trying to explain it away like that is a cop out.
A mistake is is an error or misunderstanding.
So unless you accidentally snorted coke by doing something like tripping over an extension cord and falling face-first into a pile of coke and then inhaling the coke through your nose as an involuntary breathing action - then it wasn't a mistake.
Look at it this way, is committing adultery a mistake? No. Someone doesn't accidentally stick his penis into a vagina, or confuse another woman's vagina for the vagina of his wife, that would be a mistake. Yet we hear that "cheating was the biggest mistake of my life", right?
So regardless of whether we are looking at your decision and action, or that of an adulterer, what happened was not a mistake.
What it really was is an intentional and willful act that you (or our mythical adulterer), apparently, regret.
It makes no difference if you were hammered or of clear mind when you intentionally and willfully decided to use coke and intentionally and willfully used coke, you are responsible; nonetheless.
But lets call it what it is.