Sources say the exes are trying to divide their property and negotiate custody of their kids.
Even though Nick Cannon and Mariah Carey are doing their best to keep the details of their split private, sources tell PEOPLE that their divorce is heating up behind the scenes.
On Tuesday, Carey arrived three hours late for her Rockefeller Center Christmas tree taping because she was stuck on the phone with her divorce lawyer.
"She was on the phone for probably close to five hours straight with lawyers," a source tells the magazine.
Although her fans weren’t happy about being left out in the rain, Carey had pressing personal matters to hash out with her ex.
"She would never want to upset her fans," the source added, also insisting they were "arguing over property and custody of the twins.”
Reps for Carey and Cannon did not comment. The couple wed on April, 30, 2008 and welcomed their twins Monroe and Morrocan on April 30, 2011. In August 2014 the couple confirmed their split.