Instagram/Mary Cosby & Kandi Burrus Celebrity RHOSLC star Mary Cosby mourns her son Robert Cosby Jr., 23, after a tragic death. Read her tribute and the Bravo community's support. March 15, 2026 AceShowbiz - Mary Cosby, star of Real Housewives of Salt Lake City, is grieving the heartbreaking loss of her son, Robert Cosby Jr., who passed away at the age of 23. The tragic news broke after authorities responded to a Salt Lake City home on Monday following a report of a possible overdose.