The fallout saw Hammer step away from high profile film projects, and his agency WME also dropped him. He was set to star alongside Jennifer Lopez in the movie Shotgun Wedding.
The Los Angeles Police Department opened an investigation after a woman known only as Effie accused the actor of "violently raping" her.
A family friend who spoke to Vanity Fair about Hammer's rehab stay said: "This is a clear sign that he is taking back control [of] his life and knows that this [is] a step towards his overall wellbeing."
An ex-girlfriend said: "He's addicted to drugs because he has so much trauma that he cannot deal with stillness, face himself, or sit alone with his shit.
"Everything he's doing he has essentially said out loud in a tweet or an interview. He's not that secretive.
"He's been about to explode for so long, but everyone laughs it off."
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