I think you just got really paranoid and scared. This happens to some people when they get high. I experienced it once when the police tried to bust me and a friend smoking in the dorms. Also one of my longtime pot smoking buds had to quit smoking because he just started to freak out. If there was another reason for you to be paranoid, obviously eliminate that next time you smoke. If you think it was just the weed, smoke less next time untill it becomes a good experience again.

Ive heard that you can "OD" on weed if you eat over 5 grams of hash. This wont kill you, but it can be a horrible experience and it would also cost a ton. As far as smoking the dired leaves goes, you wouldnt be able to smoke fast enough to get that amount of active thc in your system at once.