'Who's the Boss?' Star Danny Pintauro on HIV Diagnosis: It's Like Hearing You Have Terminal Cancer

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Danny Pintauro revealed that he's HIV-positive on Oprah's Where Are They Now? over the weekend, and now he's opening up about what it's been like living with the diagnosis for the past 12 years.

"It's like anybody hearing you have terminal cancer or something awful," Pintauro, 39, told ET. "My life is forever changed."

WATCH: Who's the Boss? Star Danny Pintauro Reveals to Oprah He's HIV-Positive

While the public is only now being made aware of Pintauro's diagnosis, he wasn't shy about sharing the news with his friends, including his Who's the Boss? co-stars Judith Light and Tony Danza.

"I told Judith many years ago," Pintauro said. "I tell anyone who asks. To me, it surprises me that it hasn't come out yet ... Tony was great, but I can tell he was a little disappointed for the drugs part more than anything."

Pintauro admitted that he contracted HIV because he wasn't careful and was having unprotected sex. According to the former child star, drugs played a major part as well.

"The drugs were a big problem," Pintauro said, wanting to make it clear that "child celebrity syndrome" had nothing to do with it. "It's the meth. It takes away all your inhibitions."

WATCH: Danny Pintauro Tells Oprah What Happened After He Came Out

According to Pintauro, crystal meth is an issue "specifically in the gay community that people aren't talking about."

Pintauro came out publicly as gay in 1997 after the National Enquirer threatened to out him. While his revelation came before many other stars, Pintauro said it was late enough in his life that he had already missed out on some opportunities.

"When I first came out, which was before everybody -- I mean, Ellen [DeGeneres] and I came out the same year. Rosie [O'Donnell] came out four years after I did -- I missed the opportunity to be a beacon of light for gay kids who were going through what I was going through," he told Winfrey.

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Today, Pintauro is seizing every opportunity and making the most out of his life. He currently works as a restaurant manager in Las Vegas and is married to realtor Wil Tabares.

"Life throws some good stuff at you and throws some bad stuff at you," Pintauro said. "And right now I have some really good stuff."