From your description, you are a hell of a sailor to have kept control of the boat. Pitchpoling is always a risk around and of course above 15 knots depending on the weight placement of crew, oncoming rollers, and the setting of the sail. Definitely depower the sail to spill more air. I think you have figured this out already and were wise to head home in those conditions with such a high power boat and inexperienced crew.