Instagram/Mary Cosby & Robert Cosby Celebrity Remembering Robert Cosby Jr., Mary Cosby's devoted son and confidante. A heartfelt obituary honors his unwavering faith and family loyalty. March 18, 2026 AceShowbiz - Mary Cosby's late son, Robert Cosby Jr., is being remembered as a devoted son and man of strong faith in a heartfelt obituary. The tribute highlights the unique and close relationship between Mary Cosby, star of "The Real Housewives of Salt Lake City," and her only child. Described as his mother's closest confidante, Robert Jr.'s loyalty to family was unwavering.