TLC asked psychologist Becky Beaton to help Cary organize his apartment for the hourlong episode, but when she leads him to his mother's room, Cary, riddled with anxiety, lets out a primal howl.
"I can't do this," he says on the show. "I'm stressed out. People don't understand me -- they don't get it. I can't help myself."
Only breaking into a rendition of Elvis' "Love Me Tender" calms him.
"In my 20 years, this is one of the worst cases I have ever seen," said Beaton, founder and director of the Anxiety and Stress Management Institute in Atlanta.
But for Cary, music is "his therapy," she said. "He gets comfort from singing songs … And when he starts to talk like Elvis, it's a coping mechanism."
"When he was a little kid, his mother dressed him up like Elvis," she said. "She got such a kick out of it, she entered him in contests, and he got a lot of love and affection from doing impersonations … When she died, he went off the edge."
Cary's fear of abandonment, after such intense bonding with his mother over Elvis, is at the root of his illness, according to Beaton.
His recovery is complicated by the well-meaning intentions of his closest friends and his support system, Joe and Francesca.
"My wife and I believe he needs a strong kick in the ass," says Joe in the episode.
Beaton says that their "tough love" approach to Cary exacerbates his trauma. "Yelling doesn't make it better," she tells them on TV. "Ultimatums never work. They were adamant about trying to control him, but this was really hurting him."
Moving vans arrive, to help clear out his apartment, and Beaton tries exposure therapy -- letting Cary choose which things to throw out, slowly -- but it is too traumatizing for him. Instead, she introduces a harm reduction plan, just removing items that present safety hazards, not things that are precious to him.
The movers took away 20 large trash bags in March and now, "on a scale of 1 to 5, he is about a 3," she said.
Beaton is now guardedly hopeful. Like addicts, only about 20 percent of all hoarders get better.
But today, Cary sees a psychiatrist and a therapist and is on medication. "I have cleared a lot and am making more improvements," he said. "I am doing the best I can. I haven't regressed. But it takes a lot of willpower."
But when he is Elvis, "I feel like a totally different person," said Cary. "I am giving the world back something. Elvis was the greatest entertainer with the greatest voice. A real humanitarian. People still miss him. I miss him."
"I wasn't living like a human being," said Cary. "You can't get rid of it all, but try to get rid of some of it. It's not healthy. It's still difficult for me … I'm not cured yet. But I am a little more restrained."
With that, when asked by ABCNews.com, Cary transforms his nervous demeanor and confidently belts out back-to-back two of his favorite songs, "Suspicious Minds" and "I Can't Help Falling in Love With You."
At that moment, he was The King.