A well-known record producer has confirmed what Mariah Carey suspected — her music mogul ex-husband Tommy Mottola tried to sabotage her “Glitter” album and boost the career of rival songbird Jennifer Lopez!

Rap producer Irv Gotti revealed that Mottola asked him to remix J.Lo’s “I’m Real” record using rapper Ja Rule, launching a sneaky bid to copy — and beat to the record stores — Mariah’s “If We” track. That previously recorded collaboration with Ja Rule was scheduled for later release on “Glitter.”

Ja Rule also confirmed that he was called by J.Lo’s people after they heard the song he did with Mariah.

“They thought the record (Mariah’s) was incredible. So they called me and said, ‘We want you to do a record for J.Lo. . . but we need it now.’ ” Ja Rule told the Internet site

Mottola — whose 5-year marriage to Mariah ended in 1998 — is chairman of Sony Music Entertainment, which owns Mariah’s longtime label Columbia Records.

Last year, Mariah jumped ship to EMI/Virgin records to escape Motola’s long arm. But after Mariah’s emotional meltdown last July, combined with the box-office failure of her movie “Glitter” and weak sales of the film’s soundtrack, EMI/Virgin bought out her contract and cut her loose in January.

“Mariah felt all along that Tommy was trying to torpedo her career. It helped spark her breakdown,” a source close to Mariah told The ENQUIRER.

“People acted like she was crazy and delusional when she accused Tommy. But this latest admission by Irv Gotti is proof positive.

“When Tommy and Mariah divorced it was a bitter split. And he immediately started to look for a new pop diva to one-up Mariah.

“Well, he found her in J.Lo. She didn’t have the voice of Mariah, but she had looks, charisma.

“And Tommy tired to one-up Mariah for J.Lo whenever he could.

“But Mariah’s a fighter, and she’s coming back stronger than ever.”

Mariah’s spokeswoman Cindi Berger told The ENQUIRER that the singer is doing great these days. “Mariah is in an incredibly positive space right now,” she said. “She’s recording her new album, her role in the movie ‘Wisegirls’ is getting wonderful notices from the press, and three or four record companies are aggressively pursuing her.

“She doesn’t want to dwell on the past.”