As promised, Oscar de la Renta really did sing with Barbara Walters — oh, and Bette Midler and Sarah Jessica Parker — in his Madison Avenue store for Fashion’s Night Out. SJP, who arrived a bit late, straight from the SATC 2 set, insisted she was pressed into the chorale unwittingly. “I didn’t know there was going to be singing here, period. So I certainly didn’t know that Mr. de la Renta could sing,” Parker told us after the performance. Walters said she and De la Renta had planned a duet, and they even rehearsed at her house once: “But, of course, we had Sarah Jessica and Bette, so forget the duet, we had the two huge stars.” Midler praised her fellow singers, saying, “They’re right up there with the greats.” Walters laughed and gave her own appraisal: “I don’t think that we’re going to be an opening act for Bette, unless she wants her show to immediately close down.” Witness the insanity in our exclusive video.