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fell off the wagon while performing in Las Vegas over the weekend leading him to enter rehab, a family friend tells

Claudia Suarez Wright, the ex-wife of Green Day drummer Frank Edwin Wright III (aka Tre Cool) confirmed Armstrong entered rehab today.

“He’s doing okay. He’s with his family,” Claudia told Celebuzz.

“He’s in rehab and his family is by his side.”

What did she say happened in Las Vegas?

Claudia, whose son is Billie Joe’s godchild, revealed details that led to the difficult decision to get help.

“When he was in Vegas he was drinking a lot. The night of the show he had been drinking,” said Claudia, adding that her ex-husband texted her yesterday about the band’s ultimate conclusion.

“In Las Vegas there’s a lot of temptation to drink and it’s tough to be around when you’re fighting against it,” she said.

“They have a new album coming out and it’s a demanding lifestyle. It’s very difficult.”

According to Claudia, the famed frontman had been sober for over a year.

“He’s my son’s godfather so it’s very hard for kids to see this happen. And it must be very difficult for his wife and family,” she said.

But she confirmed his rehab stint has nothing to do with the incident in Italy earlier this month when Armstrong was admitted to the hospital and forced to cancel a performance.

“He was actually sick in Italy and it was not from drinking,” Claudia said.

Billie Joe’s mother Ollie Armstrong told us recently “he picked up a bug or it was food poisoning”.

As Celebuzz previously reported, the news of him getting treatment for substance abuse came as a shock to Armstrong’s family.

“He was fine yesterday (on Saturday),” his aunt Judith Armstrong told Celebuzz. “We were on an airplane together and he was fine.”

This all unfolded after the 40-year-old rocker went off on a bizarre rant on Friday onstage during the band’s performance at the iHeartRadio Music Festival in Las Vegas.

When the band was given a one-minute warning to wrap their set, Armstrong lost it and screamed, “You’re f–king kidding me. What the f–k! I’m not f–king Justin Bieber, you motherf–kers . . I got one minute, one minute left.”

The band later issued a statement on their official Facebook page on Sunday: “Billie Joe is seeking treatment for substance abuse. We would like everyone to know that our set was not cut short by Clear Channel and to apologize to those we offended at the iHeartRadio Festival in Las Vegas. We regretfully must postpone some of our upcoming promotional appearances.”

Billie Joe is married to Adrienne Nesser Armstrong and the couple have two children, Joseph, 17, and Jakob, 14, who Claudia said are by his side.

“His mom and wife are with him to give him support.

She added, “I want to give my unconditional support in a time of need.”