The 38-year-old singer said he felt “numb” and “relieved” after posting a message on his website announcing, “I am proud to say that I am a fortunate homosexual man”.
But after he hit the send button, Martin said the magnitude of what he had done hit him hard.
Speaking on The Oprah Winfrey Show, he said: “When I realised, ‘OK I just pressed send’, I was alone.
“I was in my studio alone for a minute. My assistant walked in and I just started crying like a little baby. I started crying.”
Martin, who was born Enrique Martin Morales, announced that he was gay in March this year.
Two years earlier, the Livin’ La Vida Loca singer became the father of twin boys Matteo and Valentino via a surrogate.
Martin told Winfrey that his sons were the reason he felt he could no longer sidestep questions about his sexuality.
He said: “I couldn’t take it anymore. It was too painful.
“I guess the most important thing is my children. When I was holding them in my arms, I was like, ‘What? Am I going to teach them how to lie?’
“That was my blessing right there. Then, when I was holding my children, I said: ‘OK, it’s time to tell the world’.”
Martin’s interview with Winfrey airs in the US tomorrow.