KATIE HOLMES has caught fire with her hunky hetero new co-star, and sources say her ex TOM CRUISE is furious!

The hot-to-trot single mom didn’t hold back while filming sexually charged scenes with her “Mania Days” leading man Luke Kirby in New York recently.

And insiders say their red-hot chemistry – both on-screen and off – has sent a loud-and-clear message to Tom that Katie’s finally moved on.

“Katie put real passion into those kisses – you wouldn’t have known they were scripted,” said an eyewitness.

“She looked like she was in the throes of ecstasy.”

A source close to her told The ENQUIRER: “Katie is using ‘Mania Days’ to show the world she’s rediscovered her sexuality.

“She loved every minute of it, and it’s as if she was shoving it in Tom’s face!”

Katie wore only a skimpy blue bra top in one steamy clinch and acted obviously aroused while Luke nuzzled her chest.

In other scenes, Katie – clad in a flimsy white top – passionately locked lips with Luke, and then climbed on top of him.

Sources say the explicit poses sent Tom into a tizzy!

“He’s fit to be tied,” said an insider close to Cruise, 50. “This stuff is almost X-rated. He’s also angry that Katie never showed that same kind of passion or public displays of affection with him.”

After analyzing the photos at The ENQUIRER’s request, body language expert Dr. Lillian Glass said: “Katie is obviously very receptive to Luke.

“The fact that her knee is up and between his means that she’s engulfing him. This is a very brazen display.”

Another source revealed: “Word quickly got back to Katie that Tom was upset over the photos of the sexy scenes, but she doesn’t care anymore. She’s showing him that he can no longer control her life. They share a child – that’s all.”

In the film, Katie and Luke play a manic-depressive couple who meet at a psychiatric hospital and begin a romance. But as The ENQUIRER has reported, they seem thrilled to be together even after the cameras stop roll­ing.

On May 21, Katie and Luke, who are both 34, were spotted strolling together in New York’s Greenwich Village and later enjoyed lunch at a trendy Middle Eastern restau­rant.

They also eat lunch together in Katie’s private trailer on the set, and have holed up in her Big Apple apartment rehearsing lines, said a source.

Katie’s also changed her usual routines since hooking up with the Canadian heartthrob, sources say.

In the past, the “Batman Begins” beauty didn’t seem to mind being photographed while shopping or walking with her daughter Suri, 7.

But she no longer enters her apartment building through the main entrance, and when photogra­phers spotted her “almost holding hands” off the set with Luke, she reportedly hailed a cab and left him standing in the street.

But there appears to be little doubt a real romance is brewing.

The couple are “giggling all the time,” added a source. “Katie’s very flirty, and Luke seems to be very into her.

“She’s tired of being perceived as a single mom who will never find love again, and her relation­ship with Luke is her ticket to a new life. He’s more of a regular guy than Tom and not trying to control her life like he did.”

AS THE ENQUIRER previously reported sources say Katie was in therapy to deal with the emotional aftermath of her mar­riage to Tom and even told a pal: “Tom ruined me emotionally.”

But now she appears to be getting even by taking on a role that showcases her womanhood – with a hot young hunk! And as The ENQUIRER recently reported, Luke has a checkered past.

He stripped down while starring in HBO’s racy 2007 drama “Tell Me You Love Me,” and has a rabid following among gay men.

Sources say he also developed a crush on Katie’s former “Dawson’s Creek” co-star Michelle Wil­liams after they filmed several sex scenes for the 2011 drama “Take This Waltz.”

Meanwhile, a source close to Cruise said: “There’s still a lot Tom doesn’t know about Luke, and he’s not comfortable about that.

“Most of all, Tom doesn’t like this relationship being thrown in his face, especially since he appar­ently hasn’t found anyone else for himself.”