Given Sibyl's opinions in Act I of whether Elyot or Amanda were more at fault for the failed marriage, why is it ironic that she says in Act III, "I'd no idea anyone ever behaved like that; it's so disgusting, so degrading, Elli of all people?"

Throughout Act I, Elyot endured Sibyl's interrogation about Amanda and their marriage. He kept trying to say that he and Amanda were equally at fault for the divorce, despite Sibyl's best attempts to shift the blame from Elyot to Amanda. However, despite everything that Elyot tried to tell her, she is still utterly shocked and in disbelief when she is faced with concrete evidence that both Elyot and Amanda are equally horrid to each other. Given how Elyot spoke to her and his claims that he was just as vicious with Amanda, she really should not be surprised.