Keala Settle, best known for her barnstorming performance as the bearded lady in The Greatest Showman, is on the phone from Manchester, where she’s rehearsing for the musical Sister Act. The American will appear alongside Jennifer Saunders and Beverley Knight in a show she says is full of spirit, uplift and love. But more than a job, it’s something of a homecoming for the actor and singer, whose father is from Oldham. “This whole country, but specifically Manchester, feels like my people,” says Settle, who has moved from the US to London. “I live here. I’m going to die here and get cremated and dumped in the North Sea.”

Now 46, Settle has taken a while to find her home. She was born and raised in Hawaii, the eldest of five siblings. “We grew up with Cadbury’s chocolate coming in the post and Enid Blyton books and watching Are You Being Served?” Her mum, a native New Zealander, influenced them too. “From her, we were learning Te Reo, which is the Māori word for language, and the ways of life there. And none of it applied to the United States. So we walked out our door and couldn’t use any of it.” She saw her parents’ accents mocked and adjusted her own to sound American. But today she speaks to me with an impeccable English accent; “spongey” she calls herself, referring to her ability to soak up different cultures.

How did all that make her feel? “How did it make me feel? Babe, I left.” Settle was made to feel she didn’t belong, which was especially unfortunate as her parents had moved to a new country for a better life, with an expectation “of all the kids living the lives they never got”. It wasn’t an easy childhood. A natural singer, Settle was harmonising to TV adverts aged two. “It used to drive my mum mad! And that was our relationship for a long time. Whatever drove her mad, I was like, ‘Yes, bring it on!’ I only got into musical theatre to make my mum upset. Because she said I couldn’t act.”

Her mother wanted her to get a recording contract, but Settle ran off to study theatre instead. After landing the role of Tracy Turnblad in a tour of Hairspray, a career was born. She starred in Les Misérables and Waitress on Broadway, but it was The Greatest Showman that brought a visibility Settle never expected, or wanted. The 2017 film inspired by PT Barnum became a breakout hit, and Settle’s song This Is Me was heralded as an empowering anthem for outsiders. There’s a stirring video on YouTube, which has now been watched 82m times, of Settle singing the number at a presentation to get the film green-lit. She has said how scared she was, and you can see her quivering, hiding behind her music stand, and clutching Hugh Jackman’s hand. She’s a Tony-nominated Broadway performer – why was she so afraid?

“Because of all the background I just gave you,” she says. “I put it on display. My life has been traumatic, and that song required that. And for five years I remained traumatised so that everyone else could get enlightenment.” Settle found herself championed as a voice for the voiceless, thrust into the spotlight, with thousands of people messaging her every day. “I hated it,” she says. Were people around her aware of how difficult it was? “It didn’t matter. It’s the industry, love.”

In 2018, she had a mini stroke. “Because that’s how much trauma was happening in my body. I’ve been told that by the doctors who did the 10-hour surgery.” From her hospital room, she was fitted for a dress to sing at the Oscars – the one gig she really wanted to do – but since then she has focused on her mental health, and even finally made her peace with This Is Me. But it is not back to business as usual. While she is “really happy” to be part of Sister Act, she says: “It’s my last one. I will never do musical theatre again.”

After a recent performance in & Juliet in London’s West End, she says, “I took my bow with my face in my hands because I was so scared they would see my face. Everyone was trying to love me with their energy and I was like, ‘Get back!’ I did not want to be in the frontline, ever. My mother wanted that, not me. I’ve done so many things for so many other people. For me, I just want to bake bread and walk my dog.” Settle is borderline agoraphobic, so the dog makes her get out, “because I knew I couldn’t be afraid for ever.”

She’s booked to do panto this Christmas – a true embrace of her Britishness. Beyond that, she’s doing a bit of writing, but won’t say more. “We live in a world where it’s like, ‘What’s your checklist? Let’s see how your checklist is doing!’ I’m not being funny, but sod off!” She laughs. “Quality of life matters so much more than anything else. I just want the chance to breathe.”

• Sister Act: The Musical is at the Eventim Apollo, London, and now booking until 28 August.