The former Blue Peter presenter made the devastating announcement on Twitter, revealing she passed away just three days after being diagnosed.
Simon has now returned to his Instagram account to share a heartbreaking family snap of himself, Gemma and their young son Ethan.
In the picture, the trio are black silhouettes as they hold hands and look out over a lake, while all clad in winter coats and wellington boots.
[Simon Thomas/ Instagram]
The TV star also shared his devastating grief as he told his followers: “Team Thomas. Three has become two. Heartbroken and suffocating with grief.”
Fans shared their condolences with the presenter, with one person writing: “Reading about this hit me like a slap in the face as a reminder to enjoy everyday. Life is short. Thoughts to you and your boy.”
Another said: “I am so sorry for your loss. May you and your little boy bring each strength through the challenging times ahead.”
Antonio Carluccio has died, aged 80, on November 8 [Getty]
A third person said: “Sending you a lot of love and courage. Stay strong for you and for your little boy.”
Thomas announced the tragic news of Gemma’s death as he posted on his social media: “Today I am crushed with indescribable pain.
“Just three days after falling ill with Acute Myloid Leukaemia, my dear wife Gemma passed away yesterday evening surrounded by her family and friends.
“If you are a prayer – pray for my boy Ethan. 8yrs, precious and in bits. Thank you.”
Acute myeloid leukaemia is a type of blood cancer that affects the bone marrow.