What if Littorio had been caught at Cape Matapan?

What might have happened if the damaged battleship Littorio had been caught with the Italian cruisers at Cape Matapan?

Britain might have destroyed Littorio along with much of Italy's heavy-cruiser force, compounding Taranto into a devastating strategic loss.

The counterfactual assumes that the Italians would keep the cruiser force with a damaged battleship rather than leave Littorio with only a small escort. That decision would concentrate the most valuable ships in the path of the British night action. The result could be the loss of the battleship and most or all of the Italian heavy cruisers involved. Coming after the attack on Taranto, that outcome would sharply reduce Italy's remaining ability to contest the Mediterranean, whatever losses Britain suffered in return.