"I was like a cave man," he said. "It was a hard pill to swallow, the amazing reality that I cannot phonate well, cannot pronounce my Italian, German or Russian or that I cannot remember my music."
Jordan began therapy within the first few weeks of his stroke, but recovery was slow. He felt that he had an "iron tongue" and that it needed to be untied.
But singing involves different parts of the brain than speaking does, and he soon found that it was sometimes easier for him to sing than to speak.
"How ironic is it that for an opera singer like me to be a singer that cannot speak?" he said, before demonstrating by singing a few lines of a slow song called "Down in the Valley," pronouncing every word with care.
He speaks and sings every day to loosen his tongue.
At first, Jordan could only speak when he was especially emotional, accessing a "deep place," Arethas said. When she first told him he would have to learn to speak again, he paused and uttered a word she couldn't say in front of Gabriel.
"I've been told that's a different part of the brain that processes that type of communication," she said.
More than a year later, Jordan still sometimes trips over his words, but as he walks past singers and stagehands on their breaks, he speaks -- and sometimes sings -- almost as if nothing had happened. It takes him longer to learn a role than it did before his stroke, but he can do it.
The first time Jordan needed to perform was just a little more than a month after his stroke, because another singer had jury duty.
"I was so scared," he said. "Because onstage -- this place where I wanted to work with all the people here for years -- I thought my future here was done. Thankfully, it isn't."
He would soon perform a part in Don Carlo at the Metropolitan Opera with his wife, his parents and his doctor in the audience.
When Jordan becomes frustrated, Arethas reminds him of this performance.
"Because he had that victory, there were other victories along the way," she said. "That was one of the peaks on our roller coaster journey."