Mariah Carey & Nick Cannon's divorce'grows'while they'fight over house and custody of their twins'

They allegedly put their relationship woes aside to spend Thanksgiving together this year.

But Mariah Carey and Nick Cannon's divorce allegedly has grown contentious.

According to People, the estranged couple are fighting over their various properties and over who will get custody of their twins, Monroe and Moroccan.

The 44-year-old singer reportedly was late for her Rockefeller Center Christmas tree taping on Tuesday because she was dealing with a phonecall about the divorce.

'She was on the phone for probably close to five hours straight with lawyers,' a souce told the publication.

Fans were left waiting in the rain, and when she did finally show up, her performance was criticised for being off-key.

The insider said that Mariah 'would never want to upset her fans,' insisting that the call was important because Mariah and her 34-year-old husband are 'arguing over property and custody of the twins, [Monroe and Moroccan].'

'She's trying to keep it together,' added the source. 'She's focused on caring for her children and her upcoming five sold-out Christmas engagements in New York.'

'I think they're trying to work all these details out on property and the kids before it gets filed,' the source said, adding that the pair haven't yet filed official documents. 'They communicate because of the kids.'

The divorce may be difficult due to Mariah's $500 million fortune and their lavish homes in New York, Los Angeles, Aspen, and Windermere Island (in the Bahamas).

The former couple also share a $5 million private jet and a cavalcade of cars - including a $400,000 Lamborghini and Rolls-Royce Phantom.