The star said she felt like she had “disrespected” the idea of marriage when she separated from her husband, Simon Konecki, in 2018.
She added that “terrifying anxiety attacks” after the divorce prompted her to adopt an exercise regime that led to her losing 100lb in two years.
The US prime-time special marked her first TV interview about her new album.
It also saw the star perform a selection of new songs and classic hits at the scenic Griffith Observatory in Los Angeles, in the shadow of the Hollywood sign.
Attended by stars like Lizzo, James Corden and Melissa McCarthy, the twilight concert was the first time Adele’s young son, Angelo, had seen her perform live.
“It’s the absolute honour of my life, baby, to have you here tonight,” she said.
During the show, the star even helped a local man propose to his girlfriend, Ashley – serenading the couple with Make You Feel My Love after the stunned bride-to-be said “yes” and burst into tears.
“Thank God she said yes, because I didn’t know who I was going to sing this song to next,” Adele laughed.
The music was interspersed with interview clips, recorded in the same California rose garden where Winfrey spoke to Meghan Markle and Prince Harry earlier this year.
Broadcast on CBS in the US, the two-hour special is not currently scheduled for transmission in the UK. A separate ITV programme, An Audience With Adele, hosted by Alan Carr, is due for broadcast on Sunday, 21 November.
Here are some of the biggest revelations from the US.
“I’ve been obsessed with a nuclear family my whole life because I never came from one,” said the singer, whose father left home when she was just two years old.
“From a very young age [I] promised myself that, when I had kids, we’d stay together. And I tried for a really, really long time.”
Now 33, Adele said she first realised her marriage was crumbling when she took a personality test in a glossy magazine.
One of the questions asked, “what’s something that no-one would ever know about you?”, and she blurted out to her friends: “I’m really not happy. I’m not living, I’m just plodding along.”
“They all gasped,” she recalled. “From there, I was like ‘What am I doing? What am I doing it for?'”
Although Adele was together with Konecki for eight years, she has previously said the marriage and separation both took place in 2018.
“I take marriage very seriously… and it seems like I don’t now,” she said, remorsefully. “Almost like I disrespected it by getting married and then divorced so quickly. I’m embarrassed because it was so quick.”
Her ex-husband “saved her life”
Adele stressed that she still loves Konecki, even if she is not “in love” with him. The couple still live opposite each other in Los Angeles, and continue to co-parent their son, Angelo.
She went on to credit Konecki with “saving her life” after she became famous.
“At that time in my life, I was so young and I think I would have got in all of it. I could easily gone down some dodgy paths and self-destructed from being so overwhelmed by all of it.
“And he came in and was the most stable person I’d ever had in my life up until that point. Even now I trust them with my life.”
Adele can’t explain where her music comes from
Songs like Hello and Someone Like You have touched millions of people, but Adele confessed the power of her music is a mystery to her.
“I don’t think, as a person, I have what my singing has. I’m pulling from somewhere else [and] I don’t know how I access it.
“It’s wild, because I don’t think I’m that deep in real life,” she laughed.
Asked why she had revealed so much private information in her lyrics, Adele explained that she wanted to reassure people going through similar experiences.
“Music helps me in many situations, and I would like to do the same for people… to be reminded that they’re not alone.
“There were moments when I was writing the record, or I would listen back to something and be like, ‘That might be a bit too private’. But nothing is as scary as what I’ve been through over the last two [or] three years behind closed doors. So I’m not frightened.”
Adele reconciled with her father before he died
The singer told Winfrey that the “biggest wound” she’d suffered as a child was the “absolute lack of presence and effort” from her father, Marc Evans.
“I had absolutely zero expectations of anybody, because I learned not to have them through my dad,” she said. “He was the reason I haven’t fully accessed what it is to be in a loving, loving relationship with somebody.”
Although they were estranged for many years, father and daughter reconciled over the last three years, after Evans became seriously ill.
During that time, he confessed he’d only ever listened to her first song, Hometown Glory.
“He never ever played any of my other music,” she said. “He was like, ‘It’s too painful.'”
But the star wanted to play him one of her new songs, To Be Loved, which expressed how his absence had affected her ability to trust other people.
“It was amazing for me and him,” she said. “I think he could listen to me sing it, but not saying it – we are very similar like that.”
In the end, she managed to play him all of her new album over Zoom, shortly before he died in April.
“His favourites were all of my favourites, which was amazing,” Adele told Winfrey, “and he was proud of me for doing it.
“So it was it was very, very healing [and] when he died, it was literally like the wound closed up.”
She’s been criticised for her weight loss
Adele’s appearance over the last two years has been the subject of much speculation, after she lost almost 45 kilograms in a new exercise regime.
The star said the transformation was “mainly” about controlling her anxiety.
“I had the most terrifying anxiety attacks after I left my marriage,” she explained. “They paralysed me completely, and made me so confused because I wouldn’t be able to have any control over my body.”
After noticing that her anxiety eased at the gym, she began to go every day.
“That really contributed towards me getting my mind right,” she said,
Winfrey recalled her own experiences of weight loss, and how some people felt “upset” and “abandoned” when she first went on a diet
Suggesting she’d heard similar comments, Adele replied: “I’m not shocked or even fazed by it because my body has been objectified my entire career. I’m either too big or too small; I’m either hot or I’m not.
“But it’s not my job to validate how people feel about their bodies. I feel bad that it’s made anyone feel horrible about themselves – but that’s not my job. I’m trying to sort my own life out. I can’t add another worry. “
Her new song Hold On could be a “national anthem”
During the concert, Adele premiered three new songs from her forthcoming album, 30 – I Drink Wine, Love Is A Game and Hold On.
Winfrey singled out the latter as a highlight, reciting the lyrics: “I’m such a mess / The harder that I try, I regress / I am my own worst enemy / Right now I truly hate being me.“
“It was just exhausting trying to keep going with it. It’s a process – the process of a divorce, the process of being a single parent, the process of not seeing your child every single day. [It] wasn’t really a plan that I had when I became a mum.”
Speaking ahead of the TV special, Winfrey said she thought the song would become a “national anthem throughout the world for anybody struggling with anything”.
“That song is so beautiful and poignant,” she told CBS news.
Her son thinks Taylor Swift is the bigger star
Then six years old, he couldn’t believe how many people were at the show, “because he used to come to my stadium shows for rehearsals and it’d be empty,” Adele laughed.
But she said Angelo recently got a glimpse of his mother’s true popularity, after her latest video premiered on YouTube.
“The other day, he watched the Easy On Me video countdown… and he was like, ‘There was 150,000 people waiting!’ Then he read the comments and he was like, ‘People really like you!’.
“So he’s starting to get it a little bit, but not really.”