He said that since he shared online that his wife Gemma died aged 40 last year, he has received messages from people around the world with most telling him to 'be strong.'
However, the former Blue Peter host said in a blog post that he was "anything but strong" and it helped him to acknowledge that.
He explained: "A wonderful Christian man called Pete Grieg posted this on social media yesterday and I was really struck by it, because in every way it speaks powerfully to me where I'm at now - 'When life is tough they tell you to be strong.
Don't be strong. Be weak. Unclench your fists. Dare to vulnerable. Honest weakness takes courage. It affirms our common humanity, deepens friendship and elicits grace'.
"This is me."
The 44-year-old's wife Gemma died last November just three days after she was diagnosed with acute myeloid leukaemia.
Today's #snacknote to my boy. Maybe one day I should turn them all into a book to encourage others and raise some money for @bloodwise_uk #lightinthedarkness pic.twitter.com/AwvJk27SoC
— Simon Thomas (@SimonThomasSky) January 25, 2018
He has since shared his struggles with grief and supporting their eight-year-old son Ethan.
Commenting on why he chose to share his struggles online, he said: When I sent out that tweet the day after Gemma died on 24th November, I did it for nothing more then this simple reason - I just wanted people to know.
"I didn't do it for attention, I didn't do it to make me feel a bit better, and I certainly never expected the reaction it sparked."
In his latest post, written in the early hours of Monday morning following the "tenth week of severe sleep deprivation", he questioned if he would ever return to his career.
He said: "How can I ever sit in front of a TV camera again with the same confidence that has helped me through my career?"
Eight weeks ago I lost the love of my life. Gemma was everything - my soul mate, my rock, the wind beneath my wings and a beautiful mum. The pain of life without her is at times too much to bear but out of this heartbreak the light will shine again. Life is so precious. God Bless pic.twitter.com/wmwDmkQipM
— Simon Thomas (@SimonThomasSky) January 19, 2018
Despite admitting he was "not OK" and "really struggling", he said he would continue to share his grief to encourage others.
He wrote: "One day I will rise again from the ashes of these painful past few weeks, but for now this is me. Broken, fearful, weak, vulnerable and tear filled and if by admitting this it helps one person, then it's worth it.
"God bless you this week and don't stay strong, be you."
About 3,100 people a year in the UK are diagnosed with acute myeloid leukaemia - a type of blood cancer.
If you need someone to talk to, a listening ear or prayer, then you can call Premier Lifeline's confidential telephone helpline on 0300 111 0101.
