What does monte cristo do to sow the seeds if discontent in the villeforts houshold?

Monte Cristo does two important things to destroy the household. First, he uncovers the affair between Monsier de Villefort and Madame Danglars. In doing this he also exposes the fact that Villefort tried to kill their son together. The second thing he does is discuss poisons with Madame de Villefort. She gets the idea to poison her family from him, and he knew that she would be likely to do so.