While I'm certainly not the diet police(!), and I agree with Atopos's advice, you will probably no longer be in ketosis which is why most old timers do take a hard line with food or drink "extras". Once out of ketosis, the next temptation is far harder to resist... and we've seen many fall at the next hurdle, or the one after, if not the first.)Trust me, the diet police will not be calling around to beat you up - and you don't have to do their job for them by beating your self up.
Just throw the rest of the biscuits away, go for a walk, drink water, and you'll be fine.
Another reason is that this diet works brilliantly the first time. Even the second or third. But each subsequent restart seems harder and harder, and the results are never quite as spectacular as that first time.
While I completely agree with Maintainer and Atropos, it might be worth bearing in mind that had you not been on the diet, the resulting binge could have been a lot worse than 5 biscuits. I know that pre Dukan I wouldn't have stopped at 5 hobnobs, but if we now see 5 as a binge then that shows that your mindset has changed if that makes sense. So yes, get yourself back into Ketosis, work harder to escape the trigger next time (the more times you say no, the easier it really does become!) but be proud of the fact that you did stop. That you had the self control not to just eat and eat and eat and finish the pack!