Moira Fiore said her daughter is struggling to maintain her sobriety, People magazine reported.
"She is struggling with her sobriety and we are going away on a cruise, so we feel better that she will be there while we are gone," says Fiore.
Fiore said her daughter, 33, would stay at the unnamed facility about two weeks.
"It is a facility for very wealthy people trying to fight addictions," Fiore said. "Brooke is really trying to get her life back."
Sheen filed for divorce from Mueller last month; the couple has twin boys 18 months old.
Mueller has been working with Paris Hilton on a new reality show, and earlier this week they showed up at Las Palmas in Hollywood, riding in Hilton's pink Bentley and followed by a camera crew.
"Paris and the other girls on the show are going to Las Vegas and Brooke did not feel she could handle it now," Fiore said. "She was scared. We're all happy she will be in the facility and hope she will feel better."
Mueller spent time at The Canyon rehab center in Malibu earlier this year.
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