What is the climax of Roman Fever?

The climax of "Roman Fever" comes as the two matrons sit watching the Roman sunset, recalling events of their first visit to Rome so long ago, and both friends reveal truths that shock the other.
While the two matrons watch their daughters depart, old jealousies are awakened as Alida Slade feels that Grace Ansley likes the two girls to accompany each other all the time because her lackluster daughter Jenny acts as a foil to Alida's vivacious and charming Barbara.
Once alone in the historic spot where an old jealousy was thought to have been resolved, in the climax, Alida Slade boasts that she caused Grace to contract the Roman fever by tricking Grace into going to the forum with a forged letter from Delphin Slade, who later became her husband. Grace issues the real coupe de grace, however, by informing Alida that she responded to the letter, and Delphin did, in fact, meet her. "I didn't have to wait that night."
This climax of their old animosity reaches its resolution as the ladies rise to return to the hotel and Mrs. Ansley tells Mrs. Slade that she feels sorry for her because she did not have to wait, after all, that night so long ago. Mrs. Slade asks why she would feel sorry for her when she married Delphin and had everything--

....I had him for twenty-five years. And you had nothing but that one letter that he didn't write."...."I had Barbara," she [Grace] said, and began to move ahead of Mrs. Slade toward the doorway. ("Roman Fever")

Having had the final word, Mrs. Ansley now walks ahead of Mrs. Slade.