Regardless of how it happened, assume it did.
1. Ease mainsheet to allow boat to begin to right itself.
2. Begin furling the jib (yes, it will furl on any point of sail).
while easing its sheets.

I forget that many boats do not have all sail halyards led to cockpit
and going up onto the cabin top in a broach must be frightening. Sails
are cheap, life isnt, let em flog if necessary
Forget sillies who claim to eschew engine use. Boats have engines for
a reason, in danger, use it.

BTW, my old non-roller furling jib had a downhaul for just such
occasions for FL thunderstorms.
Would a downhaul led to the cockpit work for the main? With any force
on the main, it will not fall by itself but you can always muscle it
down unless it gets caught in the spreaders.