Paula Williamson, a 59-year-old mother and grandmother, won the huge UK Millionaire Maker prize on March 1, but was oblivious to the win until a week later.
Mrs Williamson decided that, as one of her sons, Jack, was on holiday in Australia, she would not tell him or her other son, Ian, about her winnings until the whole family was back in the UK.
Despite living in the same house as Ian, she was able to keep the news between just herself and her husband, Geoff, 68, only revealing the news to her children on Tuesday.
The emotional moment when Mrs Williamson finally unveiled the huge, £1 million cheque to her sons was captured on video, with the pair looking stunned at their mother's new wealth.
Speaking on Tuesday, she said: "There is no way we could have celebrated without our two sons being with us.
"I did tell Geoff, because that would have been so hard to keep the winning news from him, but we both decided we wanted to tell Jack and Ian at the same time.
"It was tough being in the same house as Ian and keeping it from him but we did it."
She added: "Celebrating the winning moment is something we wanted to ensure we would remember forever."
Mrs Williamson, who has worked as a dinner lady for 20 years and has no intention of retiring, hopes to use the money to buy a house each for her sons, and is also hoping to get her hands on a new three piece suite.
Having bought the ticket from a branch of Morrisons, she walked around with it in her purse for a week after the draw, unaware that it was in fact worth £1 million.
She said: "I always buy a EuroMillions ticket when I do my weekly shopping and at the same time check my ticket from the previous week.
"When I got to the till to check my ticket the machine made a noise and the shop assistant said I had won more than £500 so she couldn't pay out."
Mrs Williamson said she initially thought she had won "around £550", but said she "couldn't believe it" when she realised the scale of the jackpot.
The lucky winner added: "I keep having to pinch myself and tell myself that I really am a millionaire."
Mr Williamson, a retired long distance lorry driver, and Mrs Williamson, who have five grandchildren between them, have said they are "not going to rush into anything" and intend to "take time to think" about what to do with the money.