tohelpafriend - most studies show active nicotine clears out in about three days. Nicotine will stay in the blood stream for about three weeks then you are physically clear!!
i had a panic pack too. started bumming them out to my bf, then carried just one cigarette in my car for a long time (just in case). Then when i was cleaning out my car i saw it broke and almost had a panic attack - i quit 10 months ago!! so having the back up cig helped me mentally, just knowing it was there and when it was finally gone i realized ten months what's another day?

best of luck, hardest addiction ever!!