The Salt Lake City Police Department confirmed to ET that Mueller and her 7-year-old twins with Sheen, Max and Bob, had been found safe after they received a welfare check call on Nov. 16. Mueller was taken to an area hospital for an evaluation before entering a rehab center.
"She was in the hospital for a little bit," Wolofsky tells ET. "I do know she woke up in the hospital after detox and my mom asked her what she wanted to do at this point, and she was the one that said, 'I want to go back into rehab, and I want to stay there for a while.'"
"It was definitely her decision [to go to rehab]," Wolofsky adds.
While Wolofsky says she doesn't know "what happened before" Mueller's hospitalization, another source close to the family tells ET that much of what was reported about the Nov. 16 incident was inaccurate.
"She was never barefoot; she never hit the kids. Brooke was overmedicated at the time and was not herself," the source says, adding that Mueller's mother, Moira Fiore, has stepped in, and is now living at her house and taking care of Max and Bob "so their daily routine stays the same while Mueller is in treatment for abusing prescription drugs."
According to Mueller's sister, the twins are doing well since their mother entered rehab, and will be visiting her on Christmas. "I know that we're going to see her on Christmas. We're going to go over [to the rehab center] to visit and just spend time with her. My brother, his wife and two kids, my parents and I are going to go to Utah to spend Christmas with her," Wolofsky reveals. "Brooke would not let us show up without the boys."
"We send her pictures and videos of them all the time. Her whole life revolves around the boys, [who are] looking forward to seeing her. They miss her and really love her," she says. "They know what's going on, and that mom's getting help."
While Mueller is looking forward to being with her children, Wolofsky says that her sister "doesn't want to leave" rehab until she is truly ready.
"It's impressive how in control she gets after the fact. She's the one that's like, 'I don't want to leave for a little while, I need to really work on myself,'" Wolofsky says. "I know that she doesn't want to leave until she is [there for] a certain amount of time -- totally sober with no temptations of any kind, which is really smart on her part."
Reporting by Brendon Geoffrion and Emily Lefkowitz.