The Blue Peter presenter lost his wife Gemma in November just three days after she was diagnosed with cancer.
Sharing a beautiful picture of his 8 year old son Ethan kissing her, Simon reflected on the month with a heartbreaking post.
“Four weeks ago today Gemma entered her final hour,” he said.
“Four long weeks. Four pain-filled weeks. Four life changing weeks and yet I still can’t comprehend that she’s gone.
“I have that eternal hope, but right now it just hurts. It hurts so much, but the darkness will not overcome me. #gemma #lightinthedarkness.”
The Spy Sports presenter was flooded with messages of support from fans.
Keith Chegwin has died, aged 60, 11 December, after battling a long illness [Getty]
“Keep talking… it helps and there’s no shame. There’s buckets of empathy for you,” one wrote.
Another added: “Keep strong Simon, a lot of love for you and your family, make sure your boy has a great Christmas.”
“Stay strong Simon, both for yourself and for Ethan. In our thoughts & prayers,” wrote a third.
Simon announced the heartbreaking news that his wife Gemma had died – just three days after she was diagnosed with an aggressive form of blood cancer.
Simon told The Mirror that Gemma felt ill and visited her GP where she was advised to rest.
“She felt very unwell last weekend and we took her to the doctor’s three times, but three times they didn’t seem concerned,” he said.
The 44 year old said that she started chemotherapy on the Tuesday night, and although she initially responded well, her condition quickly worsened and she died just days later surrounded by family and friends.