The former Scottish Socialist MSP turned writer and performer says her new direction in life is as good as therapy.
She admits to having experienced very public and painful struggles with depression and anxiety over the years. For her the most powerful aid has been the theatre.
"When I left the Scottish Parliament I was out of work. I was going through a difficult time and that's when I came into contact with Rachel Jury and Catrin Evans," she explains.
"I had met Rachel before on demos but never in a professional sense. They were working with women in the communities and said, do you want to come to some workshops?
"I found it a therapeutic process, it really helped me to get well. I've been overdosing on it ever since. It's the best medicine."
Rosie went on a journey that saw her write and perform her own one-woman show at Glasgow Comedy Festival and star as herself in the play I, Tommy at Glasgow's Pavilion.
Now she has a role in post-war set The Gates, a musical extravaganza about The Gateways, a London club frequented by London's bohemian set, written and directed by Rachel and part of this year's Glasgay! programme.
Described as West Side Story meets Cabaret and Chicago, The Gates features blues, jazz and gospel-influenced music and looks at the underground scene inhabited by those living on the edge of society.
"Everyone from Quentic Crisp to Joyce Grenfell and Joan Collins went to the private members' club," says Rosie. "Because of the laws on homosexuality at the time, some of the people would have been living illegally. It was a very glamorous place."
Apart from the fabulously styled 1950s costumes and hair and make-up, Rosie says the most enjoyable part of the project has been researching the role.
"There was a whole culture of men returning from the war, things were changing and women were being thrown back into the perfect housewife role, after having worked at munitions plants and been independent. So women's roles were changing quite dramatically in a negative way, while all that was going on there was also a lot of pushing and pulling between the gangsters in London to take over clubs.
"The play depicts that struggle: these newly-born gangsters, the spivs, the bohemians and that huge clash of cultures and genders. It's a really powerful piece of work."
Rosie plays an Irish woman in her 40s, who for various reasons cannot return home and finds herself at the centre of the set who frequent the club. She worked as a cleaner but swaps her mop and bucket for the chic and elegant life at The Gates.
Singing and dancing however, is a new path for Rosie.
"I have done a few choreographed things with Rachel but never in my previous existence - I hate dancing," she laughs. "Give me a script and I'll work hard on it, give me a song and I love singing, but show me a dance and I'm like a kid at saying, I've forgotten my PE kit.
"The scenes are terrific. There's a lot of dancing: some of it is quite saucy and some is very dramatic."
Rosie joins Lorna Brooks and Noel Bridgeman in the cast and the show has a full company of 24, featuring music by Andrew Cruikshank.
She has set her sights next on re-writing her one-woman show and taking it to the Edinburgh Fringe next year.
"Working on stage is something I enjoy doing but I'm not going to pay the rent with it unfortunately," she says. "As long as I'm enjoying it I'll keep doing it."
n The Gates runs at the Classic Grand, Jamaica Street, Glasgow, until Saturday as part of Glasgay!