The Real Housewives of Salt Lake City star Mary Cosby is mourning her son, Robert Cosby Jr., after his tragic death. "I'm going to miss you, Bubs ❤️🙏😢," Mary, 53, wrote via Instagram on Saturday, February 28, sharing a throwback photo of the mother-son pair. The Bravo personality added hashtags for "God First," "Love" and "Forever," and set her upload to Jessica Mauboy's cover of "Time After Time." Us Weekly confirmed earlier this week that Robert died on Monday, February 23, after a suspected overdose. He was 23. Bravo Stars React to Mary Cosby's Son Robert Cosby Jr.