Brooke Mueller is headed to rehab. For sure this time. No question about it. We're pretty sure.

After deciding over the weekend to check in to a treatment facility in Los Angeles... only to then decide to go with outpatient care instead... sources now tell TMZ the troubled ex-wife of Charlie Sheen has chosen once and for all to seek professional help for substance abuse.

"After further reflection and consideration, Brooke has decided to remove herself from the media spotlight and has entered a long-term in-patient treatment center where she can focus on her recovery without distraction," her rep says, adding that she's already checked in to the undisclosed facility.

Mueller will retain custody of her twin boys, this insider says, explaining that they'll remain in their house under the care of a nanny.

"Charlie and Brooke’s parents fully support her decision and everyone recognizes the importance of maintaining the children's normal routine," the rep concludes.