Been there, done that and bought the (XL) T-shirt
O.K., you messed up - in a fairly small way.
The trick now is not to make it a big mess.
I have in the past done this kind of thing, then aggravated it by pretty much eating whatever I could find.
I would then feel so useless and worthless that I would just give up on losing weight altogether.
So now I am 50 and fat and it is so much harder to shift the weight when you're older.
So hang in there!!!