In an epic new blowout, Ellen DeGeneres has laid down the law to her wife, but Portia de Rossi refuses to toe the line, sources told The 

The latest blowup is over Ellen’s new multimillion-dollar lifestyle brand, E.D. Ellen wants her wife to play a role in its launch, but Portia wants to focus on her career.

Insiders said tensions exploded during a heated argument in the car Oct. 26.

“Ellen is desperate to keep talk of divorce under wraps – because she thinks that hundreds of millions of dollars are riding on it,” said a source.

“She wants to be the new domestic diva. The last thing she wants is something to go wrong. She’s convinced this will be a billion-dollar business, like Martha Stewart’s!”

Ellen plans to launch E.D. with a holiday collection. The website is expected to premiere in the spring. She’s also launching a video website for her and Portia called Ellentube.

As The ENQUIRER reported, experts said Ellen’s recent TV interview of Portia exposed “tension between the two,” confirming reports of past marriage woes that could possibly lead to a nasty $220 million divorce.