The Sky Sports presenter’s wife Gemma died in November, three days after being diagnosed with the disease.
In the clip above, Simon speaks about the moment he told his eight-year-old son Ethan that his mother had died.
“My heart was pounding. He (Ethan) went in to see her twice that day. I didn’t tell Ethan she was going.
“I just said, ‘Mummy is seriously ill’, and I held him to her ear a couple of times and he said he loved her and (then) he went to play with his cousins.
“And I got home, and I thought I’ve just got to grab him, so I took him upstairs, and I looked into his deep brown eyes and said, ‘Ethan, I’m really sorry, they couldn’t make mummy better’.
“You can’t dress it up. I just said, ‘Mummy’s died’, and he collapsed on to the floor. I collapsed with him. I just held him. I would never wish that on my worst enemy.”
Just needs to sort out his outfit and he’ll be ready to take over from his old man! pic.twitter.com/5vnbhjx8Tm
— Simon Thomas ? (@SimonThomasTV) February 25, 2018
Acute myeloid leukaemia is an aggressive and rare form of blood cancer.
The symptoms of AML usually develop over a few weeks and become more severe. It affects some 2,600 people in Britain each year.