TMZ broke the story ... Tameka Raymond asked a Georgia court last month for full custody of their twokids -- claiming Usher has continually dropped the ball as a parent ... failing to get her permission to travel with their kids, hiring nannies without her approval ... the list goes on.

Tameka also claimed Usher callously closed her Saks 5th Avenue credit card -- and now she can't take advantage of the "special benefits" the card offers.

But Usher claims it's all BS -- filing his own response in the ongoing custody battle ... asking a judge to reject Tameka's request for full custody, on grounds her allegations are false.

Usher and Tameka currently share joint physical custody of the kids.

As TMZ previously reported, Tameka has also tried numerous times to get the judge to force Usher to submit to a drug test. So far, no luck.