After several (rumor-filled) months of silence, Green Day frontman Billie Joe Armstrong has opened up about the substance abuse issues that landed him in rehab late last year, following a much-publicized onstage meltdown last September.

“I couldn’t predict where I was going to end up at the end of the night,” Armstrong told Rolling Stone regarding his alcohol and prescription drug addictions. “I’d wake up in a strange house on a couch. I wouldn’t remember how. It was a complete blackout.”

When asked specifically about last September’s tirade at a radio festival in Las Vegas, Armstrong says he has little recollection of smashing his guitar onstage and hurling expletives about Justin Bieber.

“I remember tiny things,” he said. “The next morning, I woke up. I asked [my wife] Adrienne, ‘How bad was it?’ She said, ‘It’s bad.’ I called my manager. He said, ‘You’re getting on a plane, going back to Oakland and going into rehab immediately.’”

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