Simonette DaCosta claimed in new lawsuit, filed in Manhattan federal court, that Carey, 44, forced her to work 100 hours per week but refused to pay her any overtime, reported New York Daily News.
The suit claimed Simonette "attended to Mariah's children's needs not only at home, but also during Ms Carey's travels for her global concerts and appearances."
Simonette's lawyer Eli Freedberg said, "Simonette was on call 24 hours a day. She was always at their beck and call."
According to the suit, Simonette "was always behind the scenes and often by Ms Carey's side."
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"Ms Carey would not tolerate any delay when she called and plaintiff had to attend to her every demand, spontaneous or otherwise," the suit continued.
Simonette claimed Mariah fired her in January 2014 after the 'All I Want for Christmas Is You' singer scolded her "for expressing too much affection for their children."
Eli estimated that Carey and Cannon owe Simonette around USD 100,000 in damages.
Carey's representative refused to comment on the issue, saying, "We don't comment on frivolous lawsuits.