Ne-Yo says it broke his heart to let fans down when walked he off stage mid-show at his Manchester gig last week, and he hasn't cried so hard for years.
Ne-Yo's hits include Closer, So Sick and Because Of You
The R&B singer updated his blog to say he blamed the meltdown on a sinus infection and not having had a holiday for a few years.
He says his family, music and fans are the most important things in his life and it "literally broke his heart to tell 12,000 of the people responsible for making [him] who he is that he could not perform".
"I've never had to stop a show, never dreamed I'd ever have to," he wrote. "I cried harder than I have in a very long time with no shame whatsoever.
He says he knew something was up almost immediately.
"From the first song I knew something was wrong. I shoulda stopped there, but I come from a school where no matter what, the show must go on.
"It wasn't until about four songs in that I came to the painful realisation that my voice was done, literally nothing left, and that I would have to stop the show."
On his website, he tells Manchester fans: "I love you and and I thank you for being so understanding and supportive", promising they "will receive the show [they] deserved".
But he also has a message for those who "question his manhood" for getting emotional.
"If you knew that the people you cared for the most you had to disappoint and it was your fault... and this didn't spark some kind of emotional outbreak within you...then with no shame, I'll say you are truly a stronger man than."
'Floods of tears'
Ne-Yo struggled to sing on stage for more than half an hour at the MEN Arena in Manchester last Thursday.
BBC Manchester presenter Karen Gabay was at the concert and said Ne-Yo looked like he had a "really bad fever".
She says Ne-Yo started his gig 30 minutes late and announced that he wasn't feeling well quite early on.
"Even after the second song, for a man who is normally so cool, he was sweating.
"He was doing a Michael Jackson tribute and you could see that he was actually struggling to finish every musical phrase. He kept asking the audience to bear with him.
"My friend also noticed that his songs had been shortened."
Gabay says Ne-Yo then went off for a "very long break" before he came back on stage in "floods of tears".
"He absolutely couldn't hold tears back - the crowd were applauding him and he couldn't bring himself to speak.
"Then he said he'd never had to do this before - he'd never not been able to finish a show - he said it though tears, it was unbelievable."
The R&B singer was able to perform at his other UK gigs, in Liverpool on Friday and Newcastle and London over the weekend.