AFTER diva an­tics deep-sixed her big-screen hopes, ex-“Grey’s Anatomy” star KATHERINE HEIGL has come crawling back to TV – and her foes are crowing!

Sources say the beauty, 34, and her meddling “momager” Nancy cap­sized her career with their outrageous demands and difficult behavior.

Now the star of  “Knocked Up” and “27 Dresses” has stooped so low that she’s resorting to sleep-aid TV commercials.

“A lot of people who’ve worked with Katherine say this is karma,” sniffed an in­sider.

“She and her mom treated everyone from producers and directors to script and ward­robe people badly on her way up. So they’re thrilled to see this happening to her now.”

Heigl first made waves back in 2007 when she threatened to quit “Grey’s” while negotiating a pay raise. The actress – who played Dr. Izzie Ste­vens on the show – eventually left in a snit for big-buck film roles.

But after some initial success, she made a string of box-office disappointments including “Killers,” “One for the Money” and “The Big Wedding.” And ear­lier this year, she was so desperate for work that she appeared in a ZzzQuil commercial.

According to a pub­lished report, her reputation also wrecked a recent chance for her to land the lead in a TV series.

“She would have been perfect for the role, but all of us said she’s not worth it,” noted a producer.

Since then, Heigl has signed on to do an NBC pilot about the CIA, but her future appears far from certain.

“Katherine’s wicked ways have come back to haunt her,” said the source. “This pilot may be her last chance for a comeback.”