(CNN) -- "Who's the Boss?" star Danny Pintauro revealed that he's HIV-positive in an interview with Oprah Winfrey that aired on Saturday. He was diagnosed with the infection in 2003.

Pintauro, who played Jonathan Bower on the long-running '80s sitcom, shared his secret with Winfrey on her network's "Where Are They Now?" show.

"I wanted to tell you this a long time ago, but I wasn't ready," Pintauro told Winfrey. "I'm ready now. I'm HIV-positive and I have been for 12 years."

Pintauro, 39, came out publicly as a gay man in 1997 after he said a tabloid reporter told him he would be outed with or without his consent.

The diagnosis came in 2003 after a regular checkup. "You know, as a responsible gay man, you're getting an HIV test done every six months."

The news came with a "weird combination of feelings," Pintauro told Winfrey.

"There's this awful feeling of 'I'm never going to be able to have a good relationship, no one's every going to want me.' That was there and that was prevalent. You know, that moment of 'Oh God, I'm now going to have that conversation every time I meet someone. Who's going to want to love me?'"

Fortunately, Pintauro's fears didn't stop him from finding happiness. He married his husband, Wil Tabares, in 2014.

Pintauro posted a photo with Tabares to Instagram on Saturday, apparently referring to his public announcement: "Last meal as a nobody. ;) first meal as an activist. #lifelovelive."

™ & © 2015 Cable News Network, Inc., a Time Warner Company. All rights reserved.