 The Duchess says she had planned to murder the Cardinal that very night with her own hand, but Hernando beat her to it.She drinks the antidote, as does the Cardinal (to prove his good faith), and then the Cardinal changes his tune and says the antidote is extra poison and Duchess is definitely dying and he is glad of it.The Surgeon announces that the Cardinal's wounds were not enough to kill him, and the Cardinal finds out he's actually killed himself with the poison.