"...but ...I literally just told you..."

So, opinions from DMs. The way I'm playing WDH, there's a few mysteries happening simultaneously, and the players are encouraged to talk to NPCs and remember clues. So how do you handle it when a player is earnestly asking an NPC an important question... immediately after they've already been given the answer?Example: Party found Ammalia Cassalanter crying by Osvaldo. She told them that after Neverember was ousted, nobles turned to Victoro for financial help, and then his own resources were stretched thin. He turned to Siamorphe for help, found none, and turned to Asmodeus instead. Yadda yadda "One shy of a thousand unfortunate souls" and so on, and then realizes the players will ruin her plans. Combat ensues, they defeat her. Great. Fine. Then, finally, one of the players asks her, "Why? Why did you do it?"So, how should I have proceeded here? Perform a monologue? Have the players answer his question for him? It was a really emotionally charged moment completely defused by a collective facepalm. Just wondering how you would answer the player's question in an encouraging, non-demeaning way, so that he has the info he needs.