AFTER Tiger Woods’ sexy girlfriend called herself his “wife” during an in­terview, the irate golf champ gave her a stinging ultimatum: “Shut up – or else!”

Sources say Olympic skier Lind­sey Vonn’s loose lips infuriated both Tiger and his ex-wife Elin, and now he’s terrified she’ll prevent him from seeing their two young children.

“Elin is livid!” a family insider told The ENQUIRER.

“She’s told Tiger that she wants full custody of the kids, and she’s taking steps to keep them away from Lindsey.”

Lindsey, 28, sparked the fire­storm when she gave her first interview since she and Tiger an­nounced their romance in March.

The bouncy blonde declared she was “very happy” with Tiger, and added: “We talk golf…but mostly I listen…Lots of people go home and talk to their wife or husband about their job. That’s what we do.”

When Tiger, 37, heard about Lindsey’s comments, he exploded, said the source.

“Tiger knew Elin would be furi­ous,” the insider said.

“He flew into a rage and told Lindsey, ‘You should learn when to keep your mouth shut! You’re going to cost me my kids!’

“Lindsey tried to explain that she meant no harm, but Tiger told her that if she even thinks of herself as his wife, he’s done with her.”

Tiger, who earned $78 mil­lion last year, is also paranoid that Lindsey is trying to get her hooks into his fortune, sources say.

Meanwhile, Swed­ish-born bombshell Elin, 33, has been angry since Lindsey was photographed taking Tiger’s cubs  – daughter Sam, 6, and son Charlie, 4 – to school, according to sources. The skiing champ has also been spotted fishing and jet skiing with Tiger and the kids.

“Elin thinks Lindsey and Tiger are using the kids for publicity,” said the insider. “And when she heard what Lindsey said about being Tiger’s ‘wife,’ Elin said, ‘That’s the last straw!’”

Now she plans to tackle Tiger in court, added the source.

“Their divorce agreement specifies that Tiger is not to have the kids around his girlfriends,” explained the in­sider. “Elin feels he’s violated that agreement, and given her an opening to sue for full custody.”

Tiger and Elin ended their six-year marriage after The ENQUIRER revealed his illic­it affair with New York party girl Rachel Uchitel in 2009. In the wake of that revela­tion, Tiger’s affairs with dozens of bimbos were exposed. He eventually paid Elin a reported $110 million divorce settlement.

“Elin has never taken Tiger’s romance with Lindsey seriously, figuring he’d get bored with her and it wouldn’t last a year,” said the source. “Now, however, she’s become convinced that Lindsey is trying to replace her as the chil­dren’s mother, and she’s certainly not going to let that happen.”