Two goals: First, aim dead downwind, two bows are always better than one. Second, slow the damn thing down.

1> Release the jib, now. This will pop out the bows a bit and disturb the flow on the back of the main
2> Main brakes: ram your rudders, those are good brakes when held a 90 degree of the transom. Keep control however
3> More brakes: Put a feet in the water if you are in a position to do so.
4> Stall the main by sheeting in your traveler (I'm assuming that the main sheet is already pretty tight), but if you are already in the hole, it is unlikely you will have enough time to stall it enough. If one of you has its hand on the downhaul it's probably a good idea to yank it in real tight as well
5> Move back! Hold on something!
6> Pray.

Been there, done that: I did not save it either. It was some seven or eight years ago and the memory of it is still vivid...