It looks like things may be getting a little heated between Nick Cannon and Mariah Carey as the two work out the terms of their divorce. According to a source at People, Carey was late to her recent performance at Rockefeller Center due to an almost five-hour phone call with her divorce lawyers, “arguing over property and custody of the twins.”

The singer’s Christmas Tree Lighting performance came under scrutiny this week when the unedited version of her vocals hit the Web. Failing to hit the notes in her holiday classic “All I Want For Christmas Is You,” Carey’s appearance led some viewers to suggest that she hang up the mic. And while she did not address her singing, the did take to Twitter to apologize for her lateness:

Mariah Carey
Echoing Cannon’s sentiments that he and Carey “communicate because of the kids,” the source also told People that the ex-couple is trying to iron custody and property out before filing divorce papers.

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