10. What did Margeurite do when her evidence against the Marquis St. Cyr came out?

She keeps the information hidden from her husband. Armand asks whether Lady Blakeney has told her husband of the full circumstances of her denunciation of the Marquis de Cyr's family to the tribunal -- circumstances which apparently exonerate her from all blame. But Lady Blakeney says she has not, and as a result, her relationship with her husband has been destroyed.