"But I never ever dreamed that I would be playing her - and I remember when I heard about the audition for it, I was too scared to allow myself to get excited about the possibility... because it's so, so tough.
"Just to book a leading lady role… it's not an easy thing to do. So when they told me I'd got it, I screamed. I screamed and screamed and I couldn't believe it. And then I had to keep it a secret… I couldn't tell anyone!"
The 28-year-old first came into the public eye as a Eurovision hopeful - finishing fifth in 2009 - and was a member of Sugababes from 2009 to 2011. But Jade told DS that she now feels like "a different person" to the one who found fame in a girl group.
"I just wanted to sing but I didn't really have a sense of self and I very much went with what everyone else told me I should be doing," she said.
"You need to feel happy and fulfilled and you need to sleep well every night. Since being back on stage, it's really made me appreciate that this is what I was supposed to do.
"The fame stuff should always be a byproduct. But when that - and all the propaganda and the gossipy stuff - is the focus, and the performance thing is secondary? It kind of feels, to me, pointless. I don't get enjoyment out of that.
"I feel really happy doing press now, because I'm doing something that I'm really excited about. I'm happy to sit and do interviews, and I'm relaxed. You feel smiley and proud and positive. It's a really nice feeling."
She's since won rave reviews for her musical theatre work - including the Regent's Park Open Air Theatre production of Porgy and Bess, and In The Heights on the West End.
But Jade - who stars opposite Dean John-Wilson in Aladdin - is reluctant to ever rule out a pop music comeback.
"If music comes back up in the future, I'm going to do it and I'm going to commit to it 100%. I will never say I'm not going to do that again, because I've learned quite quickly that nothing ever goes to plan!"
See Jade Ewen in Aladdin at the Prince Edward Theatre, London, with previews from Friday, May 27.