Who is Lady Bradeen from Tales of Henry James: The Texts of the Stories, the Author on His Craft, Background and Criticism and what is their importance?

Lady Bradeen's character appears in the story, In the Cage. She is described as a beautiful, petite English lady, who is married to the wealthy Lord Bradeen and having an affair with Captain Everard. The couple often communicates with telegrams written in code. Eventually, Lord Bradeen discovers his wife's adultery, but he dies before he can make a scandal. In the end, Everard and Lady Bradeen marry.