The reality TV star has voluntarily checked into a trauma facility on the East Coast, her representative has told Us Weekly.
The news comes hours after New York Post editors released new footage which appeared to show Mueller doing crystal meth in a van in July, 2018.
According to the police report from the day of the incident, her nine-year-old son, Bobby, was left alone in a hotel room at the time.
Mueller shares Bobby and his twin brother, Max, with Sheen. The pair filed for divorce in 2011.
The one-time realtor has battled substance abuse and mental health issues over the years.
Sheen, who celebrated one year of sobriety in December (18), has yet to comment on Mueller's decision to seek treatment.