EXCLUSIVE: Sizemore Headed to Celebrity Rehab, Faces Heidi Fleiss

RadarOnline.com has learned that troubled actor and addict Tom Sizemore is headed to rehab and television--simultaneously.

Sizemore will join this season of VH1's Celebrity Rehab, a source tells us. Not only will he battle his addictions, he'll face former girlfriend Heidi Fleiss--who he was convicted of assaulting in 2003.

"Tom showed up wasted yesterday at the Pasadena Recovery Center and was put in 'lock down,' for serious withdrawals," a source tells Radar.

Fleiss has been onsite filming for some time, long enough to make enemies, we're told. And how did she react when her former flame was added to the cast?

"Heidi...went straight to her room and didn't comment," the source says.

They also expressed that the show's host, Dr. Drew Pinsky, personally sought out Sizemore to join in the sobriety efforts. Black Hawk Down actor Sizemore was originally set to appear in the show's first season in 2007.

Season three went into production at the end of April, and recently announced a spinoff series dealing exclusively with sex addiction.