Sue, who had her daughter Freya when she was 57, said she now wishes that she had had children sooner.
Now aged 61, she revealed to Closer magazine that she was recently hospitalised after contracting a blood infection which left her unable to cope with her four year-old for several weeks – including over Christmas.
She said the experience has made her believe that the cut-off age for having children should be 50.
The retired teacher told the magazine: "It's so true that you learn from your mistakes, and my mistake was not having her sooner.
"I was so ill, I literally thought I was dying. I kept thinking about Freya – and for the first time, I realised I might not be there for her any more.
If I'm completely honest, my experience has taught me that 50 should probably be the cut-off limit for having children. But, until you have them, it's almost impossible to appreciate that.
Sue, who lives off her pension in a two-bedroom house in Harold's Wood, Essex, also told how her decision to become a mother in her late 50s has seen her facing a backlash from other parents.
She caused controversy in 2008 when she had Freya, via IVF, using sperm from her partner and a donor egg.
Critics blasted Sue, saying she was too old to become a parent – but at the time she claimed she had no regrets, and even said she would love to have another baby.
Now she is feeling the strain of looking after her daughter, especially after splitting from her partner Nick Mayer, 49, a warehouse manager, last year.
She also revealed how she has been openly criticised by other parents, with one mother at Freya's crèche telling her that she was 'selfish' because Freya would be bullied.
"I was in tears, it made me feel very vulnerable," said Sue. "Once, I took Freya to see a health visitor and she thought Freya was my granddaughter. I was so embarrassed."
Sue revealed the strain of being an older parent to an energetic youngster.
At my age, I get exhausted easily – especially since I've been ill. I was 57 when I had Freya, but I felt very energetic and able to cope
"I hope I live to see Freya go to university and get married and have a family of her own. That's my only wish now."
Sue became pregnant in June 2007 after three rounds of IVF. She and her partner had spent £15,000 on fertility treatment in Russia after they were turned away from British fertility clinics because of her age.
Russian doctors decided she was fit to bear a child using sperm from Nick, but that she would need to use a donor egg.
Freya was born in March 2008 by Caesarean section.The little girl stays with her father every other weekend, and he looked after her when her mother was ill.
The infection which made Sue ill last year is still in her blood and could damage her heart if it returns. It was at first misdiagnosed, and doctors said she would have died if she had left it longer to be treated.
If Sue should die, she has arranged for Freya to be looked after by her niece in Norway as her ex-partner works full-time.
In November Parentdish.co.uk reported how Sue had said there should be no upper limit on mothers having babies. But recent experiences have certainly changed her opinion.
Earlier this week we reported on the sad news that Britain's oldest dad had died at the age of 78 before his youngest child's first birthday.
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