In an interview with Holly Willoughby and Phillip Schofield on ITV's This Morning on Tuesday he said he was in hysterics.
When asked how challenging it was to tell his eight-year-old son about his mother's death, Thomas said all he could do was scream.
He said: "I left the hospital... she died at 5:45pm on a Friday night and we left about an hour later. "And we came out of the hospital, I think I woke up every patient there because I just screamed.
"I'm a Christian. I'm a man of faith, I screamed to God 'why, why have you left my boy without a mum?'"
He added that when he arrived home and told his son, who was heartbroken.
"All the way back [from the hospital] my heart was pounding," Simon said. "He went in to see her twice that day... I held him to her ear a couple of times and he said that he loved her.
"I looked into his deep brown eyes and I just said, Ethan, I'm really sorry, they couldn't make mummy better. "You can't dress it up and I just said 'mummy's died'."I took him upstairs looked into his deep brown eyes, I just said they couldn't make mummy better," Thomas said.
"He collapsed onto the floor, I collapsed, we were rolling on the floor and I just held him."
Thomas' wife Gemma died in November after being diagnosed with an aggressive form of acute myeloid leukaemia. Thomas later revealed that his wife was pregnant at the time of her death.
Since his wife's death, Thomas has been using his blog and social media to discuss grief and how his Christian faith has helped him.
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