Angela Lansbury's first husband, actor Richard Cromwell, was gay. They were married from 1945-46; Cromwell died in 1960. Long after that, Lansbury revealed that the marriage ended because of Cromwell's sexuality.
Former college and women's professional basketball player Carolyn Moos almost married her fiance, Jason Collins, until he came out as gay in 2012 while they were still engaged; Moos says she was crushed by the revelation. Collins later became the first openly gay player in the NBA.
Jackee Harry of Sister, Sister fame and her husband from 1996-2003, Elgin Charles, who later came out as gay, had a short-lived reality show Beverly Hills Fabulous, about his hair salon; they stayed close and she even appeared on the program
Diff'rent Strokes cast member Charlotte Rae divorced her husband, John Strauss, after he came out as gay in 1976.
Everybody's Boy Meets World crush Danielle Fishel wasn't actually married to NSync member Lance Bass, but they did date for over a year and she did say she was blindsided after he came out.
Phyllis Gates' marriage to actor Rock Hudson came to an end Gates learned that Hudson had not only had an affair while filming on location, but had it with a man. After he died, Gates wrote that she had no idea that he was gay, but his friends have claimed she knew all along.