In April 1858 Wagner's wife Minna intercepted a note from Wagner to Mathilde and, despite Wagner's protests that she was putting a "vulgar interpretation" on the note, she accused first Wagner and then Mathilde of unfaithfulness. After enduring much misery, Wagner persuaded Minna, who had a heart condition, to rest at a spa while Otto Wesendonck took Mathilde to Italy. It was during the absence of the two women that Wagner began the composition sketch of the second act of "Tristan". However, Minna's return in July 1858 did not clear the air, and on August 17, Wagner was forced to leave both Minna and Mathilde and move to Venice.