The Who's the Boss? alum chose to come out of the closet in 1997 when the National Enquirer threatened to out him, and he quickly became a "beacon of light" for the gay community – whether he was ready for it or not.
Nearly two decades later, Pintauro tells PEOPLE he's taking on that mantle in earnest as he addresses an issue that is not only very personal to him but also a challenge for the LGBT population.
The former child star, 39, sits down with Oprah Winfrey on Saturday's episode of Oprah: Where Are They Now? to reveal several secrets he's been harboring for years, including his past abuse of crystal meth, how he used the drug to explore his sexuality and the destructive impact he's seen meth have on the gay community. For Pintauro, these problems are deeply intertwined, and he's hoping Saturday's news will ignite a conversation that could stop a resurgent epidemic.
Caught in an EpidemicIn an exclusive clip from the episode, Pintauro tells Winfrey he began using in 2003 because he wanted to test some of his personal, sexual boundaries and that "crystal meth takes away your inhibitions – you have no limits."
But, Pintauro tells PEOPLE, with that boldness can come a recklessness: "You're never satisfied with what's happening in front of your right then," he says. "You end up usually spending 12 to 18 to 24 hours and beyond awake with very little sleep, if any at all, trying to continue the experience, trying to continue the high."
Then still transitioning between his acting career and figuring out "what I wanted to be when I grew up," Pintauro began using regularly for about three years. He has since done extensive research on meth use in the gay community and has realized that his own dependency coincided with an epidemic among his peers.
And with the rise of dating sites that paved the way for apps like Grindr, Pintauro says, "The number of guys you're going to find online at 4 o'clock in the morning is pretty significant, and a large percentage of those guys are also doing meth. You have plenty of options."
Pintauro, then 26, was just out of a two-year relationship and was open to testing the limits of his sexuality, including experimentation with BDSM, and he found crystal meth was an immediate means to do so: "On crystal meth, you have no boundaries, you feel invincible. You feel incredibly heightened when it comes to your sexuality, and everything sounds and feels exciting to you," he says.
Pintauro ultimately realized he had a problem when he began relying on the drug every weekend, trawling dating sites in an "out-of-control" haze for up to an hour at a time and experiencing "severe" come-downs that would incapacitate him for days at a time.
"It would make me so angry with myself that I had done it and that I was now suffering through this three-day period of nonsense that I couldn't even go to work or find a job or make something happen or even make myself some food. For me, that was so deeply upsetting, and it made me so angry that that was enough."
Though he hasn't used regularly, except for a few regrettable relapses, since 2005, Pintauro admits that "it's the kind of drug where years and years and years and years later, I still have cravings."
A Beacon of LightMostly out of the spotlight since his 1997 coming-out, Pintauro says he realizes that this new return to the public eye "kind of comes out of nowhere and throws me into a pool of people that no one has ever expected that I would be a part of."
But, now that he has matured and found direction in life (including marrying partner Wil Tabares in 2014), he hopes to reclaim the "beacon of light" role he wasn't truly able to embrace when he was in his early 20s.
"It is definitely one of my life regrets that I wasn't able to take that [responsibility] on," he says. "So now that all of this is happening, I feel like the fates are telling me that this is my opportunity to be that beacon of light, and I'm going to do everything and anything I can to live up to that."
And though Pintauro envisions an overall positive outcome for his new mission, he knows it will be rough going at first, both personally and publicly.
"The one reaction that I know is going to happen for sure – the one that really makes me the most sad and the one that I really can't do anything about – is the disappointment that I didn't live up to that short list of child celebrities that haven't gotten involved in drugs or alcohol in some way, shape or form," he says. "The disappointment is going to hurt the most."
In a way, though, Pintauro says that criticism is exactly what he hopes and expects will come, even if it stings: "Look, if you want to say nasty things about me or call me a meth head or whatever the nonsense may be, I'm all for it. Because if anyone's going to call me that, then technically they're also calling the people that I'm trying to help that. So this isn't any negativity that I'm not ready for – and, in fact, it's probably going to fuel my fire. The judgment's what's going to make the difference."
And that shock tactic will be mutual: "I feel like one of the ways the community is going to listen is for me to be pretty harsh. It's not going to be, 'Hey guys, let's work on fixing this.' It's going to be, 'Get your f---ing s--- together,' pardon my language," he says with a laugh.
Still, Pintauro admits that he's "getting more and more terrified every day" leading up to Where Are They Now? because the revelations to come will launch a new chapter in his life that's daunting, invigorating and even a bit redemptive.
"I've never really been an activist. I was always, like, one step above neutral when it came to any topic over the years," he admits. "And I feel like that's partly why I'm so fired up – because I have a lot of time to make up for."
Oprah: Where Are They Now? airs Saturdays (10 p.m. ET) on OWN.