Gemma Thomas died in November 2017, just three days after being diagnosed with acute myeloid leukaemia, a type of blood cancer that affects the bone marrow.
He told BBC Breakfast that telling their son Ethan, eight, about his mother was "the most crushing, brutal thing you will ever have to say to anyone".
He added: "I think, as the weeks have gone on, the reality of daily life, of mum not being around, has begun to hit home.
"He finds it difficult when he's alongside families, where he's with his friends that he's grown up with for the last eight years, and for the most part he's playing like he would have done any other time, but quite often when it's home time or they leave, he goes very quiet and often the tears begin to flow.
"Because he sits there and while he's enjoying himself, the brutal reality of seeing his friends still with a mum, still with a dad, hits home."
Discussing his Christian faith, he said: "It's the biggest test it's ever had.
"If I take God out of the equation, the faith that I've had throughout my life, then the hope disappears because the hope is that one day I see Gemma again."
He continued: "In my limited experience so far, you cannot get through this and not be changed.
"The only question is what kind of person are you going to develop into and my hope in this - and hope is a the centre of how I try and deal with it - is I will try and come out a better person."
Thomas added that he has discovered that people in the UK find it difficult to talk about grief.
"I just think so often in life we want to present that strong front, but I've learned in the short time I've been going through this is we don't like talking about grief in this country.
"We are not a society that does grief very well, but you know what? What I have begun to understand is that people do want to talk, they just need permission to talk."
On May 20, Thomas celebrated what would have been his wife's 41st birthday, sharing a photo on Twitter and writing: "To the girl I struggle to live without. Happy Birthday. I will never ever stop loving you xx"
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