It was less than 20 minutes to curtain on opening night of Verdi’s La Traviata and over 3,000 audience members had nearly all taken their seats at the Metropolitan Opera last December.

Stephen Costello, one of the most in demand young American tenors in the world, opened the door to his dressing room backstage and grabbed the first person he saw in the hallway—his dresser Lou.

“You have to get the stage manager in here. I can’t sing.”

“What?” said Lou.

“I can’t sing. Something’s wrong. You have to get somebody, you have to get them now.”

At 15 minutes after curtain, stage manager Gary Dietrich walked onstage and announced to the audience that there was a delay.

Five minutes later he announced that Francesco Demuro, who was scheduled to take over the run two weeks later, would replace Costello.

Canceling last minute at the Metropolitan is no small matter. It was also Costello’s role debut at the Met, the most important opera house in the country.

Principals can get paid upwards of $15,000 a performance at the Met, and an audience, some paying over $300 for a seat, kept waiting for 20 minutes is, while not completely unheard of, very rare.

“They did a performance that night but I wasn’t there. That’s the short version,” Costello told The Daily Beast in an exclusive interview.

“Honestly, the whole night is a blur. I remember warming up, singing through my music, feeling OK. And just warming up, warming up and then all of a sudden I did something and my neck got really tight. I remember thinking ‘oh my god’— it felt almost like something in my throat had popped.

“Then I couldn’t sing. Nothing would come out. Then, as they were calling me to the stage to get ready and walk on…my neck went into spasm, my throat and all the muscles around it just got so tight…I could barely talk. It was frightening because I thought there was more wrong, I thought something had happened on my vocal cords or something when it was just a muscle spasm—not in my vocal cords but around my neck and I couldn’t sing, I lost my voice, I couldn’t get anything going—and it was all from stress.”

Costello had not shared with anyone the full reason for his stress: he and his wife were separated and planning to divorce.

In 2008 Costello had married soprano Ailyn Perez, another fast-rising American operatic star.

Young, attractive, and fiercely talented, they had been rising stars each in their own right, but their marriage accelerated the buzz surrounding them and cemented their position as the young “it” couple of opera.

They both won the coveted Richard Tucker Award, he in 2009, she in 2012, and are the only married couple to have ever done so. The award is given, says its website, “to an American singer poised on the edge of a major national and international career, and it is hoped that the award acts as a well-timed catalyst to elevate the artist’s career to even greater heights.”

The beginning of their love story seemed equally enchanted. They met while attending Philadelphia’s elite Academy of Vocal Arts together and when Costello proposed, at the top of the John Hancock Building in Chicago, he flew in both their families to be part of it.

Highly acclaimed performances around the world together led to their being dubbed “The Jay-Z and Beyoncé of Opera” by Vanity Fair and to the recording of their hotly anticipated “Love Duets” album in late 2013.

On the accompanying press and concert tour for the album in late spring 2014, marital problems began to surface.

While Costello could not comment on the exact reasons for the divorce because it has not yet been finalized, he did speak at length on the emotional and physical toll the marital conflicts had on him.

“You’re constantly in the public spotlight, and you’re trying to handle your career and you’re trying to handle your voice, you’re trying to handle everything at the same time you’re trying to deal with this,” Costello said.

“When your job depends on the state of your body and the state of your emotions and how you feel day in and day out it’s going to affect it no matter what. Some people can compartmentalize this stuff; I can’t do it. And being onstage singing opposite the person you’re trying to deal with doesn’t help.”

Costello’s stress brought on acid reflux, a backward flow of stomach acid into the esophagus, which can irritate the vocal cords and make it very difficult, if not impossible, to sing.

The first public crack in the fairytale façade occurred at a concert in mid-September 2014 at the Kennedy Center in Washington, D.C. toward the end of the Love Duets concert tour.

Costello walked out of the concert after the first few bars of the opening duet with Perez and she was forced to finish the concert solo.

“I had reflux that was so bad my throat was fried. I came on. I was singing halfway through my duet and I couldn’t do it. I think I even said the words, ‘OK, I’m done.’ And I walked offstage.

“The stress was just too much of me being out there trying to pretend everything is fine. How can you sing songs and pretend that you’re in love with someone knowing that you’re divorcing them at that point? I ended up sitting on the steps of the Kennedy Center and I couldn’t leave.”

“I didn’t know what I was going to do next. And that’s when I started into my spiral of depression. When you’re depressed, you don’t want help from anybody…and you don’t realize you’re doing yourself a lot more harm.”

Flash-forward six weeks and Costello was preparing for La Traviata at the Met.

It was his debut role in the largest opera house in the country as the male lead in what is arguably the most popular opera in the world.

He increasingly isolated himself in New York during the rehearsal period, even having pizza alone in his apartment on Thanksgiving.

“I put so much pressure on myself for that Traviata. I had just got to the tail end of my reflux related to the divorce and being stressed out all the time. I was carrying a lot of anger and a feeling of ‘I have to do it, I have to do this on my own’…It was just a bad point in my life. Not trusting people, not believing you have anyone there to support you. I did have people, but I just didn’t know they were there.”

One of the few people who knew the full story was Costello’s cousin Brian Costello. They grew up together in a working-class area of Northeast Philadelphia.

Brian’s dad Pat co-founded a boxing club for underprivileged teens from the neighborhood with their uncle, Tim, named the Jack Costello Boxing Club after their father, Costello and Brian’s grandfather.

At the opening of the boxing club in 1996, Stephen sang the national anthem for the inaugural exhibition fight, in which Brian fought. They were 15.

Born less than a month apart, Costello and Brian grew up together having sleepovers every weekend, watching horror movies, and eating pizza. Costello’s interest in music started in sixth grade; Brian played the saxophone and Costello “wanted to be like Brian,” so he took up the trumpet.

Brian, sober since 2010, lives in their grandmother’s old house in the Tacony section of Philadelphia right down the street from the boxing club with his wife, Nicole, and two children.

When Costello first decided to divorce he called Brian, who flew immediately to be with him in Chicago.

In the midst of his Traviata cancellation crisis, Costello called Brian again, just after he had pulled out of the first performance, and the second one approaching.

Brian told The Daily Beast, “He called me and I could barely hear him. He had such a depressed tone. He felt like he let people down.”

Brian told Costello he had to let go of everything that happened prior, and the stress of worrying about what people thought and how things looked. He came to join him in New York, and attended Costello’s second night of Traviata, Brian’s first opera at the Met, and the first opera he had seen Costello in.

Brian gave Costello the 24-hour AA coin they had given him the day he left rehab. “I told him what happened yesterday or last week doesn’t matter anymore. What happens tomorrow isn’t his concern yet. Just focus on today. These 24 hours.”

Costello, though not in recovery himself, was deeply moved by the gesture, and kept the coin in his pocket for the whole performance.

Brian was nervous too. “I could barely sit still in my seat. I knew how much it meant to him and I wanted him to feel good not just doing it because he felt like he had to. So I’m sitting there waiting and he came out and absolutely killed it. He ran all over the stage, jumped over couches…He sang his ass off.”

In an odd and poetically satisfying twist of fate this past August, Costello stepped into a concert performance of Traviata at the Hollywood Bowl for Francesco Demuro, who had stepped in for Costello at the Met last December.

Costello’s divorce from Perez continues to move forward; they recently sold the house they once shared in Tennessee near where her parents live.

He took part of this last summer off, staying with his parents in Northeast Philadelphia and driving with a friend to Las Vegas to celebrate the birthday of his voice teacher, Bill Schuman.

When asked about dating he had no comment but said he was in “a happy place.”

Costello just finished a run at the Met as Percy in Donizetti’s Anna Bolena. He has another role debut at the Met, beginning October 20, as the Duke in the Met’s updated Rat Pack-inspired production of Verdi’s Rigoletto.

“Where I am compared to 10 months ago is night and day,” Costello said, “I’m optimistic. I enjoy every day. I enjoy waking up every day. I look forward to the future and I’ve rediscovered the love of singing. I’m in rehearsal singing every day and I love it.”

It’s doubtful Brian will get another last-minute call, but if he does he’ll be ready.