A Moral Dilemma While Spelunking

There is a group of 6 people spelunking in a cave, one of which is a 7 month along pregnant woman, and a 8 year old child..  We came in one part of the cave and traveled about a mile underground. The tide is rising and it's too far to reach the entrance now, and we are forced to leave out of a smaller exit which is closer. We have the pregnant lady leave first so that us five can take care of the gear, and help her out. Unfortunately she gets stuck on her way out and will not be able to move until emergency help comes. The tide is rising quickly now, and it will soon drown all of us except the pregnant lady, as her head is sticking above the water line. One of our hikers is a hunter who always carries a knife, and who is experienced with dismembering game animals. We can not get her out of the exit without using the knife which will inevitably kill her; but if we don't use the knife the five of us will die, including the child. You are the leader of the group. What would you do?