We see Catherine again at the end of the story. What does Nick tell us she does?

From the text:

They had difficulty in locating the sister, Catherine. She must have broken her rule against drinking that night, for when she arrived she was stupid with liquor and unable to understand that the ambulance had already gone to Flushing. When they convinced her of this, she immediately fainted, as if that was the intolerable part of the affair.