Dancing with the Stars has been rocked by yet another sex scandal involving two of its most popular contestants-married dad Drew Lachey and his partner Cheryl Burke.

The Season Two champion couple had an affair during the show’s nationwide tour which ended last month, insiders tell Star.

“They didn’t go very far to cover it up,” one tour insider says. “Cheryl was constantly draped all over Drew. They held hands, had their legs intertwined and were always touching inappropriately.”

Cheryl’s then-boyfriend Matthew Lawrence (yup, the 1990′s sitcom “Blossom” guy’s brother) discovered his girlfriend was cheating when he walked in on the pair, catching them in the act, according to several sources.

Now insiders fear that Drew, father of a 2-year-old girl, could find his marriage to high-school sweetheart, Lea, wrecked.

“Drew Had To Be Restrained”….Sources say Matthew found his girlfriend cheating when he went to retrieve something from her dressing room as the tour hit Jacksonville, Fla. on January 22, an eight-week-long Star investigation uncovered. They say he ran out screaming after seeing Cheryl and Drew having oral sex.

The witnesses further the torrid romp saying that the next day, as tour members prepared to get on the bus to leave town, Drew had to be restrained as he ranted at Matthew and his brother, Joey in the parking lot. “If you talk about this, I’ll bury you Matt. I’ll bury you Joey. I’m serious I will hurt you,” he screamed.

One word…WHOA!

[Star Magazine]