The former Sky Sports personality's 40-year-old wife Gemma died in November last year just three days after being diagnosed with leukaemia.
Speaking about the importance of faith and his new partner, the father-of-one told Anna Foster on BBC Radio 5 live: "Right from the early stages - she had this empathy towards me. She's Christian as well and that's important to me as a man of faith.
"She's been an incredible support for me. She was the only person who would always pick up the phone."
Thomas, 45, has frequently spoken about his grief on social media, admitting in the past that he is "really struggling".
He also previously asked people to pray for his son who he described as "in bits".
Although Thomas said he was in "the early stages" of his new relationship, he had strong feelings for his new partner.
"I'm getting there, yeah," he said when asked if he was in love.
"It's in many ways strange to feel that way again."
Another Friday. Another week since these two last saw each other. As the world moves on around us, Ethan's words to his teacher this week tell of the long road he has ahead - "I've got a long long wait until I see Mummy again." pic.twitter.com/K96vSVO4qg
— Simon Thomas (@SimonThomasSky) March 23, 2018
"Sometimes I struggle with the phrase 'moving on' - I don't think you ever really do move on from what's happened.
"That hole that a loved one leaves doesn't shrink over time. Life begins to grow around it. You begin to deal with some of the challenges grief throws up, being a single parent throws up.
Thomas said his son Ethan motivates him to "find life again".
He explained: "I've got two choices. Give up - I can't do that, I don't want to do that, I've got a boy to bring up, I promised Gemma... Right from the start I felt I've got to find life again."
"This person is helping me define life again, helping me to feel happy again ...For most people we lose, they won't want us to remain in this empty landscape of grief."
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