He did issue an apology and a promise to make it up with a free show in the future. But thanks to a feature in our sister paper, LA Weekly, we now know exactly what happened that night.
See also: Review: Hopsin at the Bluebird
The anecdote appears at the very beginning of Rebecca Haithcoat's (excellent) story:
Hopsin ran away in January. Deeply depressed, he was on tour in Fort Collins, Colorado, when he decided he couldn't perform that night. Other rappers might booze it up, pop a Xanax or bed groupies to cope. But Hopsin doesn't drink, do drugs or cheat on his girlfriend. His only escape was to escape -- literally. So he removed his signature white, glow-in-the-dark contacts, tightened the strings around his black hoodie, switched off his phone and slipped out the back door of the venue.
"I pretended I wasn't Hopsin," the 29-year-old rapper says. "Something bad was going to happen at that show. I felt like I would've gone onstage and peed on all the fans or something."
She goes on to describe the reprieve he eventually felt:
Still, he couldn't force himself to turn around. He stumbled upon a house under construction, went in and laid down. Eventually he called a local friend, who picked him up and let him crash at his house, where they watched Finding Nemo. "I know I messed up," he says, adding that he plans to make amends by throwing a free show in Fort Collins. "[But] it was the only night I went to bed peacefully on that tour."
It's a great story; we advise you to read the whole thing. And you'll be glad to know that he's feeling stronger now. He's got a new relationship that's going well, and he's shaken off the depression he was feeling early this year. "I get it out in my music. I found my outlet," he told Haithcoat. "It makes my life better. I'm good."