08/07/2013 at 11:20 AM EDT
Two days after a scary pool accident
's oldest son, Usher V, to the hospital, the 5-year-old is doing "okay," according to his mother, Tameka Foster. But the drama may not be over yet.
Foster has requested an emergency child-custody hearing to regain primary custody of the couple's two children, Usher V and Naviyd, 4, reports TMZ
"Now that it's sunk in, she is livid," says a source close to Foster. "Usher has custody and won't let Tameka have the kids, even when he's out of town. She feels like the kids are being raised by his family or by nannies, when they should be with their mother."
"This is the straw that broke the camel's back," the source continues. "She could have had the boys [Monday], and they would have been fine. She knows that accidents happen with kids, but she should have been with them."
After a bitter custody battle last year, Usher won primary custody of his two sons with Foster. She has limited custodial rights.
"My son is okay, but I have no further comment at this time," Foster told CNN on Tuesday
Asked whether her lawyer had filed a motion for an emergency custody hearing, Foster had no comment.