Not usually as long as this but it can go a day or two over the date.
If the cracked egg is hatching, you should be able to hear the chick cheeping. Since it's not making much progress, you might want to help. Wrap the egg in a flannel soaked in warm water and wrung out; then gently try to pick back the shell where it's broken. If it starts to bleed, stop - it's not ready. This might be enough to give the chick a way out. Sometimes if the shells are thick, they struggle a bit.
If you have an egg light, it would be worth candling the eggs to see if you are waiting in vain. I always leave mine in the incubator for a couple fo days after the date but, to be honest, I've never had any hatch more than 24 hours after the due date.
Good luck - I know how you feel.