02/27/2013 at 08:00 PM EST
Last September, Billie Joe Armstrong made headlines when, during his band Green Day's performance
at the I Heart Radio Music Festival in Las Vegas, the rocker unleashed a profanity-laced tirade that took aim at everyone from the concert's promoter, Clear Channel, to Justin Bieber
The meltdown forced Armstrong to enter an outpatient rehab program for a month and in the latest issue of Rolling Stone
, the frontman, who turned 41 this month, reveals his struggle to get sober.
"I'm a blackout drinker," he reveals. "That's basically what happened [that night]."
Leading up to that infamous performance, Armstrong was struggling with a dependence on pills for anxiety and insomnia, combined with a heavy drinking problem. After the concert, he agreed to enter an outpatient rehab program for a month.
Although he declines to specify what type of medications he was taking, he tells the magazine, "I started combining them to a point where I didn't know what I was taking during the day and what I was taking at night. It was just this routine. My backpack sounded like a giant baby rattle [from all of the bottles inside]."
Armstrong, who has been married to wife Adrienne since 1994 and has two sons, Joseph and Jakob, also reveals how hard it was to go through withdrawal.
"That was gruesome, laying on the bathroom floor and just feeling like ... [pauses] I didn't realize how much of that stuff affected me." He also opens up about the toll it took on his family: "I kept [the withdrawal] away from my sons pretty good ... [And my wife] knew the deal. I'm sure it was rough for her to see me going through this."
Now, the musician insists he's on the mend and no longer drinking. "I want to put on good shows," says Armstrong, who will resume touring with Green Day on March 10 in Pomona, Calif. "I want to be reliable."
Armstrong also admits maintaining his sobriety will be a challenge. "There is still the obsession for alcohol," he says. "There's also sleepless nights. But I have to work on it every day. Because I know what goes on out there … I've got to watch my step."