'Real Housewives' Star -- $75k Victory in Child Support War with Ex-NFL Star

Former NFL star Bob Whitfield has 21 days to fork over $75,000 to his reality star ex-wife Sheree Whitfield for overdue child support ... or else.

According to legal docs obtained by TMZ ... Bob admits he failed to make 38 monthly child support payments of $2,142 to the "Real Housewives of Atlanta" star ... more than $81k.

Bob claimed he simply didn't have the money -- and had asked the court to lower his obligation ... but that was denied.

Now, the two sides have struck a deal in which Bob has agreed to hand over $75k before Nov. 11 ... or face the consequences in court.

In addition to the $75k, Bob has also agreed to pay $1,000 per month for the next 12 months -- before reverting back to the original $2,142.