Paris Hilton, Brooke Mueller to Co-star in Reality Series

Insiders for Sheen's ex reveal where she's been.

Brooke Mueller is no longer undergoing treatment for her substance addictions. In fact, reports an insider, she's preparing for a new reality series on Hollywood "lifestyles"...and starring with none other than Paris Hilton.

TMZ caught the report after tracking Brooke Mueller's whereabouts -- where's she been since she and Charlie Sheen last appeared in court to fight over their kids? She's been shaping up -- physically, not emotionally -- to launch her TV career.

READ: Charlie Sheen, Brooke Mueller Sign Divorce Papers

Brooke Mueller insiders revealed that Mueller has been working on herself at an"intensive, physical fitness program in Southern California"...and it's not any kind of detox, rehab or "stress management facility."

READ: Charlie Sheen's Police Reorts, Brooke Mueller Suffered Head Trauma

In fact, TMZ reports: "Brooke is involved in a cable reality show that will co-star Paris Hilton and others -- the theme being 'lifestyles.'"

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It's vague on purpose, guys...and it's suddenly no wonder Paris Hilton has been positioning herself in the spotlight again, even if so unfavorably. And while Charlie Sheen keeps the kids, it's sounding like the cast of the Brooke Mueller/Paris Hilton reality show are the ones who need a babysitter.

Flip through our Paris slideshow. Does she fit on the small screen with Charlie Sheen's ex?