During the decade boy-band heartthrob Nick Carter spent abusing drugs and alcohol—typically downing half a bottle of hard liquor a night, often followed by what he calls "a bump" of cocaine—there wasn't anything that could make him stop. Not a 2002 arrest after a Florida bar brawl or a 2005 arrest for DUI. Not his ballooning weight, which shot up to 224 lbs. in 2006, or the self-loathing he felt after a May 2008 trip to Russia, when he competed with locals to see who could down the most Sambuca. "There were things that were happening, proving that maybe what I was doing was out of control, all sorts of crazy stuff," Carter admits. "But every time those red flags would come up, I'd appease people in my inner circle and make them think everything was all right."
Even when it became clear that everything was most definitely not all right—last spring, during the European leg of the Backstreet Boys' tour, he began experiencing a mild discomfort in his chest—Carter would not stop partying. "I was thinking, 'Something is physically wrong with me,'" says the 29-year-old singer, who in June went to Ft. Lauderdale cardiologist Richard Polakoff for two days of medical testing. But the night before his results were due back, "I went out and I just went nuts," he recalls, staring out at the Pacific Ocean through the windows of his high-rise condo in Santa Monica. "I drank so much and did a bunch of blow. I felt like I was trying to kill myself—because I didn't want to get the results."
Carter had good reason to be afraid: The years of abusing his body had left a buildup of toxins in his heart, weakening the muscle so that it had difficulty pumping blood. This condition, known as cardiomyopathy (see box), is the same one that led to the death of singer Andy Gibb and killed actor Chris Penn—and Carter learned it could kill him as well if he didn't get clean and sober. "My doctor said, 'You need to change your lifestyle. I don't want you to end up like that,'" Carter says. "I was like, 'I don't want to end up like that either.'"
In the eight months since his diagnosis, Carter has indeed taken dramatic steps to turn his life around. He has lost more than 30 lbs. (see box) and—with the exception of a few slips early on—stopped drinking and doing drugs. "I don't want to die," he says. "I don't want to be that person people read about and think, 'That's sad that he couldn't stop it and killed himself.'"
Yet Carter admits that committing to a clean lifestyle remains a daily challenge, perhaps because his self-destructive behavior was a lifetime in the making. The oldest of five children born to Robert, 56, and Jane, 49, Carter says alcohol was always around when he was growing up in Jamestown, N.Y., where his family owned a bar called the Yankee Rebel. "If you want me to be honest, I had my first drink when I was 2 years old," says Carter.
Easy access to alcohol was only part of the story. As revealed on the short-lived E! reality show House of Carters, family life for Carter and his siblings—Bobbie Jean, 27, Leslie, 22, and twins Aaron and Angel, 21—was tumultuous. "There was a ton of fighting between my mother and father," he says. "The kids would be thrown into the middle, to choose sides." The dysfunction only intensified after Carter found success as "the cute one" in the Backstreet Boys, which he joined at age 12. "Fame is a lot of pressure, especially when you're responsible for your entire family," he says. "Financially, emotionally—everything."
And while he was out touring the world, his home life was falling apart. Not only was his parents' marriage breaking down, but rumors—never proven—had started to surface that the Backstreet Boys' former manager Lou Pearlman was behaving inappropriately with some of his boy-band charges. (In 2007 Jane Carter told Vanity Fair that "certain things happened and it almost destroyed our family" but stopped short of specifying how it affected Carter, who did not want to discuss Pearlman with PEOPLE.)
By 2003 Carter's parents had split, and a tug-of-war over Aaron, a teen pop star, ensued; at one point Aaron considered filing for legal emancipation. He also accused his mother, who comanaged him for 10 years, of stealing $100,000 from him. (She denied the charge and they settled the dispute a month later.) "We tried to make it seem like there weren't problems," says Aaron, "and then when there was some sort of argument or fight, it really showed."
Looking back, Carter refuses to point fingers. "It was never a one-way street. You can't just blame one person," he says. Yet the turmoil led to Carter being estranged from his parents and siblings at various points throughout the years. To cope, he drank himself into a stupor; he also took up marijuana in his late teens before entering what he calls "my Ecstasy phase," eventually moving on to abuse pills, particularly the prescription painkiller Vicodin. Then, in his mid-20s, friends on the Hollywood party scene introduced him to cocaine, which he would take to get through all-night clubbing. "I would get tired because we were partying so much, so I would do a bump [of cocaine] just to wake myself up," he says. "I would be that person who would stay at these clubs till the lights come on and they're playing "Don't Stop Believin.'" People are looking at me going, 'Is that Nick Carter?' And I'm like, 'Yeah, it's me, gacked up.'"
Yet in a way, his life had never been better. In 2002 he released a solo album that went gold; a year later he embarked on a high-profile relationship with Paris Hilton
. But that relationship unraveled seven months later amid accusations from her friends that Carter had hit Hilton (a charge he vehemently denied to PEOPLE at the time), and by the time the Backstreet Boys reunited in 2004, it was clear, say his bandmates, that Carter was struggling. "Sometimes the last people you want to take advice from are the people closest to you," says bandmate Howie Dorough, 35. "Nick was on a journey to find himself. When he was scolded, rather than motivating him, he curled up and crawled into a darker hole."
Carter's drinking wasn't the only thing out of control: Although a teenage diet of fast food and candy meant Carter had always been "a little bit overweight," in 2006 he hit an all-time high of 224 lbs., a direct result of his partying. "Healthwise, I was feeling gross, getting bigger," says the 6-ft. Carter. He recalls a particularly raucous night of partying in Hollywood that fall, during which he and a friend "did a bunch of blow" before deciding to take a bus back to his place. "We were walking past a school the next morning, and we look like zombies, and I just remember these kids looking at me, and I felt so disgusted."
The episode prompted Carter to seek help, enrolling in an outpatient treatment program. He then stayed sober for six months before relapsing; over the next 18 months, Carter found himself trapped in a wicked pattern where he would quit drinking cold turkey for a few months, followed by a few months of "hardcore drinking. It was off and on, off and on," he says. "I thought it would show people that I did have control over it, that I wasn't an alcoholic."
Even after his cardiomyopathy diagnosis, Carter struggled to accept that if he wants to live, he can no longer drink alcohol. Although he is in therapy to help cope with his addictions, there have been a few times, he admits, "where I started to drink, like, a couple of glasses of wine, and I couldn't control it." A blunt talk with his cardiologist set him straight. "Once you get this condition, it can get progressively worse until the heart is extremely weak," says Dr. Polakoff. "But if he abstains from alcohol and other substances, I think we can get his heart back to normal."
Today Carter is sober, living in a two-story, colonial-style home just outside Nashville ("I had to get away from the temptations" in L.A., he explains) and in the best shape of his life. And while he has not spoken to his father recently, Carter says their relationship is intact, and he is repairing the rift with his mother. "It's a process, and something that's going to take years to mend," he says, "but we're moving forward." Things with his younger brother have also improved, so much so that Aaron moved in with Carter last summer. "I tell him all the time, 'You're a completely different person than a year ago,'" says Aaron. "Then he was irritable, unhappy. And now he's happy, fun to be around."
The biggest change, however, is that Carter is looking to the future instead of at the past. About to complete a Backstreet Boys world tour, Carter and his bandmates are also recording a new album. And although his parents' divorce proved scarring enough to lead Carter, who has been dating a salesgirl for the past few months, to say, "I don't believe in marriage," he could see himself starting a family "someday, a little ways down the line."
For now Carter's focus remains squarely on himself and his recovery. "I'm trying to make myself better," he says. "But I don't regret anything that I've gone through, because it makes me who I am."
Go behind the scenes of Carter's photo shoot at people.com/nick_video