Step away from the sweets NOW!
Chances are it won't put you out of Keto, but it might have brought you into a milder state of it, don't worry too much though as you'll have no glycogen stores and so long as you don't eat anything else besides the packs you'll be back in full-keto in a very short time.
What made you eat the sweet though?
And why that sweet and not something else?