MARIGAY’S VENUE: Life goes on for Marigay McKee following her unceremonial departure from Saks Fifth Avenue last month. According to a source, McKee’s engagement to billionaire Bill Ford will be celebrated May 21 at the Neue Galerie on 86th Street, co-founded by Ronald Lauder. The invitation is said to be inspired by the famed portrait of Adele Bloch-Bauer by Gustav Klimt, owned by Lauder, which became the basis of the movie “Woman in Gold.” The former Saks president “has received a lot of offers to do things. She hasn’t decided what she is going to do,” said the source. “Obviously, she’s spending time with her fiance.” Ronald Lauder is the younger brother of Leonard Lauder who has long been McKee’s go-to-guy for counseling, in good and bad times.