Mueller and Sheen were married in 2008 and are the parents of twin toddler sons. The couple filed for divorce in November. Their marriage will be officially ended next month.
Sheen was fired from TV's "Two and a Half Men" in March because of his erratic behavior and substance abuse.
TMZ said Mueller, who has been in and out of rehab in recent years, is again seeking help for her addiction issues after going on a drug binge last week and refusing to take a drug test Friday.
The test was a requirement of her custody settlement with Sheen.
Sheen's lawyers are heading to court Tuesday to address the issue, TMZ said.