Hey JG,
You are not the first to come back from a professional lunch a bit altered. ;) Also, you were not alone, so you have safety in numbers on your side, I am sure.
The fact that you don't make this a habit...and that you came clean to your boss right away speaks to your integrity...and tells me that your job won't be in jeopardy.
Try not to worry about
it, but get to work early and ready to be productive on Monday!
S.C.