"When I showed up on set and I got in the makeup chair, I told everybody," he recalls. "I was like, 'I'm freaking out. I'm on this. I'm on that.' They were like, 'You need to stop. Don't tell the world that you're on drugs right now.'"
He said he managed to keep it a secret from family and friends for about 18 months, until his bandmates staged the intervention on July 8, 2001.
"The most crucial part of that conversation was the final thing Kevin [Richardson] said to me: If I continued using, he said, 'I will never trust you again. You're dead to me.'"
But AJ admitted he continued to fall on and off the wagon for the next 18 years — until one jarring encounter with his family last December snapped him out of it.
"I was never sober. Not for a second," he told GMA. "And the turning point for me was when I came back home, my wife could smell it on my breath and my youngest of my two daughters would not sit with me."
Since that day, the "DWTS" alum — who shares daughters Ava, 6, and Lyric, 3, with wife Rochelle — said he has been completely clean and sober.
"There's too much to live for today — my beautiful children, my amazing wife, my career, my brothers," he said. "I've never felt more grounded than I do today."