Eileen Murphy says the money she was ordered to pay Mike Weirsky after the divorce is now just "pocket change" for him.
The winning ticket was sold last year at a convenience store in a suburb of the South Carolina city of Greenville.
The money will be returned to participating states if not claimed in time.
The winning ticket was sold in South Carolina, the state's lottery website said.
After no winning tickets were sold for Friday night's draw.
The numbers are 15-23-53-65-70 and Mega Ball 7.
The chances of winning the jackpot are roughly 1 in 303 million.
The jackpot is the second-largest in U.S. history.
The big win comes a day after a single winning Mega Millions ticket, worth $450 million, was sold in Florida.
How would you change your life If you won $970 million?