Maybe just listen to the egg for an inner peep as someone saidCould be single or double then. If it's single it's gonna be a MONSTER chick...lol
I would give it at least 2 extra days after "hatch day" before locating the air cell & gently piercing it with a knife or safetypin & flipping back just enuf shell to see inside. Then you will know where to go from there on assisting.
Is the egg moving or was it?
I do understand how you feel totally...dont want to kill one but If this is day 2 after the hatch then maybe you should try to see whats up by doing as Nsamsel suggests Just to see if anything is moving at all NOT open it all the way yet to see whats up..Cant hurt at this point to just take a peek and evaluate.