Final answer:
Mrs. Slade reveals a long-held secret to Mrs. Ansley in Edith Wharton's 'Roman Fever.'
Step-by-step explanation:
In Edith Wharton's novella 'Roman Fever,' Mrs. Slade reveals a long-held secret to Mrs. Ansley. This revelation is central to the story's dramatic tension and explores themes of jealousy, rivalry, and the complexities of friendship. The secret relates to a past romantic intrigue involving the two women and the same man, and it significantly alters the dynamics of their relationship.