Page 16 of the core rule book
deStroying ShipS
When the number of Damage cards dealt to a ship is equal to or greater than its hull value, the ship is immediately destroyed (faceup and facedown cards count toward this total). Immediately remove the destroyed ship from the play area, discard all of its Damage cards to a faceup discard pile next to the Damage deck, and return all of its tokens to their respective supplies.
This doesn't say that you have to reveal your crits. If I had a decimator that just died without ever taking a crit, I would have 12 face down damage cards on it. Now if I pushed them all into a little pile and then flipped that pile over into the discard pile, wouldn't I be in compliance with this rule? At the same time I've only revealed the crit that was on the bottom of the pile.