Jennifer Lopez‘s volatile marriage continues to spark controversy – after The ENQUIRER caught her in what seemed to be a stony-faced showdown with her husband Marc Anthony!

Shocking photographs snapped on New Year’s Eve show sour-faced Marc apparently pointing his finger in J.Lo’s startled face.

The superstar couple continues to deny they’re having problems, but sources say they have fought bitterly and fear Marc’s controlling ways may have stretched their 4 1/2-year marriage to the breaking point.

And insiders say if they do split, there could be a bitter showdown over their fortune, estimated to be $350 million, plus wrangling for custody of their nearly year-old twins.

J.Lo, 39, and Marc, 40, have been showing a united front in public in a bid to shrug off reports that their once idyllic marriage is on the rocks. But the strain seemed to be showing with an explosive argument at a  New Year’s Eve party in San Juan, Puerto Rico.

The couple started the night at boxer Oscar De La Hoya‘s mansion, and then moved on to La Concha’s ritzy, invitation-only bash that guests watched as the glamorous beauty and her salsa-singing hubby dropped their smiles.

"Jennifer and Marc partied in the outside lounge surrounded by a close-knit set of friends and heavy security," revealed an eyewitness source at the party.

"They danced a little bit as they stood near each other, but it was nothing serious like a long romantic dance or anything.

Then Marc’s mood suddenly seemed to take a turn for the worse.

"At one point Marc took Jennifer to the side and got very serious with her," revealed a hotel staffer.

"It looked as if he was giving her some kind of orders – like a father scolding a child. It didn’t look like a nice conversation. Put it this way – no one was smiling, and it was the biggest party of the year!"

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