Her“astonishing and passionate” nine-year-old son suffered a fatal allergic reaction to his regular breakfast cereal.
And now Emma Wileman has set up a charity in Haydn’s name to try to prevent other families going through such an ordeal.
The youngster who “lit up places with his smile” went into anaphylactic shock after eating nuts in his morning cereal in September last year.
No one knew he had developed the allergy and his desperate mother tried to save him believing he was having a severe asthma attack.
It only took half-an-hour from him eating the food to him going into cardiac arrest.
Now the 35-year-old wants other parents to be aware of the warning signs of allergy and is fundraising for research into the links between allergies and asthma, hay fever and eczema.
She is working with Professor Somnath Mukhopadhyay, chair in paediatrics at Royal Alexandra Children’s Hospital, on how to promote and fund his research into the links.
Ms Wileman, who has four other children, has set up Haydn’s Wish – which she hopes will be a lifesaver.
She said: “We want to get across the information that allergies do go with asthma. They can come out of nowhere.
“He had had that breakfast cereal before. It came completely out of the blue.
“I would urge parents to watch out for the signs. His asthma had improved slightly and he had been signed off from hospital the year before.
“Parents need to watch out for signs and changes such as small patches of eczema.”
She also advised mothers and fathers to listen to what children do not like, such as nuts, as it could be a sign that their body does not like it either.
Last week a bench dedicated to Haydn was unveiled at Southdown Junior School in Newhaven, where he was a pupil.
Ms Wileman said: “He was such a passionate child. He was either the best day ever or the worst day ever. He lived his life with passion.
“His imagination was astonishing. He was so special.”
Professor Mukhopadhyay, chair in paediatrics at Royal Alexandra Children’s Hospital, said: “These (allergies and conditions) are extremely common conditions for young children, particularly in the UK.”
For more information on the charity and upcoming events visit www.haydns-wish.co.uk.