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ABC News' Bianna Golodryga and Taylor Behrendt report:

From Ashton and Demi, to Kim and Kris, and Arnold and Maria, it's been a year of high-profile divorces in  Hollywood, but the split between power couple Jennifer Lopez and Marc Anthony after seven years of marriage  seemed to be a relatively amicable one - at least where the children were concerned.

Now the claws just may be coming out, according to Us Weekly magazine. Rumors are swirling that the once amicable exes aren't so friendly anymore and that they're headed for a fierce custody battle.

"The original agreement when they split was that J.Lo would have primary custody of the kids, but since this has all come out, Marc is looking to have joint custody," said Us Weekly magazine's Rebecca Bienstock.

Anthony is reportedly furious over photos of Lopez and her new squeeze, backup dancer Casper Smart, frolicking seaside with the couple's 3-year-old twins, Max and Emme, while on vacation in Hawaii over Thanksgiving.

"Sources close to Jennifer told us that Marc is not that interested in having joint custody of the kids," Bienstock said. "He's really just using them to get back at her because he's so angry that she's moved on."

Since announcing their plans for divorce in July, the "American Idol" judge has been spotted around the block with actor Bradley Cooper, and most recently, 24-year-old Smart. Anthony is reportedly "furious" that Casper, who has been arrested for drag racing, was driving their twins around, Bienstock explained.

Lopez and Anthony's representatives have not responded to ABC News' request for comment.

Anthony will reportedly spend the upcoming holidays with the twins, but with the New Year fast approaching it could be a bitter 2012.

"Things are really going to get nasty between the two of them," Bienstock said.

However this custody battle plays out, Lopez has said that her kids will always be her first priority.

"So long as they are happy and healthy," Lopez told "Extra," "I feel like I am doing a good job as a person."