Alex Best, 47, was found to be three times the legal limit following a minor collision while at the wheel of a Mini Clubman in Waterhouse Lane, close to her home in Kingswood, Surrey, last month.
Former Manchester United and Northern Ireland player Best died of multiple organ failure aged 59 at Cromwell Hospital in west London on November 25 2005, following years of alcohol addiction.
His ex-wife, dressed in a black blazer and black trousers, entered a guilty plea to the drink-driving charge at Guildford Magistrates' Court on Friday.
She was disqualified from driving for 24 months, given a 12-month community order and told she must carry out 60 hours of unpaid work.
The court heard that Best's breathalyser reading was 106 microgrammes of alcohol per 100 millilitres of breath - the legal limit being 35 microgrammes.
Before sentencing, magistrate John Elford said: "There's many people that are killed every day by drink-drivers."
Prosecutor Darren Matravers said a two-vehicle collision, in which no-one was injured, took place at around 8pm on April 6.
He said a second call was made to police after concerns about whether one of the drivers was "intoxicated or not".
Mr Matravers said Best was "just over three times the legal limit".
In mitigation, Robin Falvey said "she is a person who never drinks and drives" and that she has "never been in trouble before".
Mr Falvey said Best had been shopping when she received a phone call from a friend who invited her to join them in a pub.
He said she had "what she described as spritzers", adding: "She realised that she should not drive."
Mr Falvey pointed out that it was the day of the Grand National and Best had spent a "considerable amount of time" trying to get a cab, adding that a friend tried too.
"That is when she made the bad mistake and drove," he said.
Mr Falvey said that both drivers had stopped and exchanged details after the collision.
He pointed out that it was Best who contacted police initially.
"She was the one that put her head in the lion's mouth," he said.
"It was this defendant who phoned the police. She reported the fact there was an accident."
Mr Falvey said Best then stopped a car and got the driver to park in front of her to alert other road users.
It was at this point it is believed a second call was made to police to raise concerns about Best.
Mr Falvey said she co-operated throughout and underwent all tests.
"She is absolutely devastated by what has happened," he said, adding that the consequences will have a "huge impact" on her life.
He said she lives in a remote area and will have to sell her cottage home.
Mr Falvey said Best is unemployed but pointed out that a man sitting at the back of the courtroom is writing a play about George Best and she is a script editor on it.
Best did not respond to questions from reporters when she left court.
Earlier, Mr Falvey said she was "absolutely remorseful".