"I hate losing the team," she said at a news conference.
She later added, "It feels good. It would have felt good to own the team, too."
The NBA Board of Governors had previously approved the sale.
"Really excited in a pretty hardcore way to continue the path to making the Clippers a better and better basketball team, and a better and better citizen of the Los Angeles community," Ballmer told The Associated Press in a phone interview.
The bizarre drama began in April when a recording surfaced of Donald Sterling scolding his girlfriend for bringing black men to Clippers games. The audio spurred the NBA to ban Sterling for life and fine him $2.5 million.
Sterling was apologetic after the audio recording went viral, but his mea culpa backfired when he criticized Lakers great Magic Johnson, who had been photographed with Sterling's girlfriend, as a bad role model for kids because he had HIV. The 80-year-old real estate mogul was roundly condemned from locker rooms to the Oval Office, where President Barack Obama called Sterling's remarks "incredibly offensive racist statements."
With the NBA threatening to seize the team and auction it, Sterling initially gave his wife of 58 years permission to negotiate a sale but then refused to sign the Ballmer deal. He said he would sue the league instead and then revoked the trust, which his lawyers said killed the deal.
Shelly Sterling removed Donald as a trustee after doctors found he had symptoms of Alzheimer's disease. Adam Streisand, Ballmer's attorney, said Tuesday that Superior Court Judge Michael Levanas signed the order authorizing the sale even if Donald Sterling's attorneys filed an appeal.
Pierce O'Donnell, Shelly Sterling's attorney, said at the news conference that Donald Sterling had filed a petition opposing the sale.
"They're alleging the judge made errors," O'Donnell said. "We believe it's another desperate act. We're confident the court of appeals will not take the case."
Streisand said even if Donald Sterling seeks an emergency order directing the judge to vacate his order, the attorney is confident an appellate court would agree that Levanas made the correct decision.
Donald Sterling's attorneys weren't immediately available to comment.
Doc Rivers would possibly have quit as coach if Sterling remained the owner, interim CEO Richard Parsons had testified. All-Star point guard Chris Paul, who also is president of the Players Association, might have sat out and convinced other players to join him. Sponsors who already started to flee after the Donald Sterling recording was released might have stayed away for good.
None of that appears to be a problem with Ballmer taking over what could be a powerhouse team next season. By agreeing to the record purchase price, he's already proven he's willing to spend in contrast to the famously frugal Sterling, long regarded as the worst owner in the NBA.