She added that he does not have a good relationship with his mother, and said Miss Foster is determined to fight for custody.
The two divorced in 2009 and both sides admitted the current co-parenting arrangement is not working.
They have been attending Fulton County court week, with both giving testimony.
Usher, whose surname is Raymond, told the court on Monday last week that he tries to focus on his children when they are with him, but sometimes he has to juggle other commitments.
According to the The Atlanta Journal-Constitution he said: 'I try to do all of my work when I don't have the children, but there may be times when there's an obligation of something that comes up.'
The hearing was taking place two weeks after the death of Foster's son. Kile Glover, who suffered a major brain injury on July 6 after a man on a personal watercraft ran over the 11-year-old and a 15-year-old girl while they were on an inner tube on Lake Lanier.
And last Tuesday Miss Foster said Usher's visitation times were thrown into chaos after the accident.
She said: 'Of course, there was no provision for visitation regarding the death of a child.
'I'm sorry I didn't stick with my visit days, but my son passed.'
During questioning about her early life, she admitted to stealing nappies and writing a bad cheque when she was a single teen mother, having her first son when she was 19 years old.
She said: 'Yes, I stole things. I stole diapers before. I've gone in 7-Eleven and stolen diapers out of the store.

'I admit it. I was 19 years old. I'm not proud of it. I wouldn't do it now.'
And she also said she has turned her life around, and is now a successful business owner.
The stylist, who has previously worked for the likes of Lauryn Hill, also claimed she had begged her ex-husband to withdraw his petition numerous times.
She said: 'I was like, "It's ridiculous, are you mad at me? I don't know why.

"You know your kids are fine. They're happy. They're productive."
'Maybe I don't do everything perfectly, but I do the best I can.'
She had previously claimed Usher did not care about her or Kile during the days after the accident
In a filing, she stated that during the 15 days the boy was on life support, he 'visited Kile in the hospital only once.'
Miss Foster also revealed she begged her ex-husband to tweet "Please pray for Kile," but he refused to do so.
Read more:
Usher ordered to reopen ex-wife's credit card by custody case judge | Mail Online
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