Mary J Blige is feeling the cold. It is a sunny autumn day in London, but the air conditioning in her hotel room is turned up high.
These desperate times call for distinctly unglamorous measures, so she has bundled herself up in the fluffy bathrobe that was hanging in the wardrobe, the plain white outerwear concealing the razzle dazzle of her outfit underneath - a fuchsia asymmetric top, purple leather trousers and a wide patent burgundy belt, set off by blue earrings and tumbling blonde curls.
This look, bathrobe aside, is in keeping with the Mary J Blige we know - the performer, the show-woman, the winner of nine Grammys, the queen of hip hop soul. And it is this persona she had to put away completely to take on her most challenging movie role to date, in the new Netflix film Mudbound, and this role of Florence Jackson, the wife and mother of a family of sharecroppers in the segregated Deep South, that saved Blige (46) from her own personal agony of a brutal divorce.
"Mary J Blige the business, not the person, is the manufactured, material, vain person," she admits. "So I had to shed her once I saw Florence's wardrobe.
"When I found out I couldn't wear any lace-fronts and I couldn't get a perm and I couldn't wear lashes and I couldn't wear nails, I had to shed the manufactured business Mary.
"Once I shed her, it was easy for Mary to say 'You know what? I'm going to give every piece of darkness that I'm dealing with right now, because I have some challenges in my life as well, so I'm going to give you all of this heaviness and all of this sadness and insecurity and feeling inferior because this is what you've been told in this bad situation and I'm going to give it to you. But I'm also going to give you Mary's strength that she gained, so you can have all these different things'. So once I committed to Florence, Florence started saving Mary's life."
It was while she was filming on location in Louisiana that Blige's marriage to manager Kendu Isaacs was falling apart. In July last year, she cited irreconcilable differences as grounds for divorce.
"What I was channelling was all of the sadness that I was feeling," she confesses. "I'm in the middle of a divorce now and during that time I wasn't divorced, yet I just was in the middle of 'something's wrong and I just can't prove what's wrong but I'm sad and I'm miserable and I've been sad and miserable for about five years now'.
"So I just gave that five years of misery to Florence. I said 'I've got to survive this thing' because it was too heavy, so I gave all that to Florence."
In the film she plays the mother of a young man, played by Straight Outta Compton's Jason Mitchell, returning home from the Second World War, who strikes up an unlikely friendship with a white fellow veteran, played by Garrett Hedlund.
The role, of an enduring, loving mother suffering the agonies of separation from her child and then terror and horror when he is subjected to the evil brutalities of the south's deep racism, helped Blige find a way through her own struggles.
"It helped and it's helping," she says. "I'm still in the process of all this madness that I'm in, and this movie is really helping me be happy because it's another chapter, it's a new chapter and I'm leaving this one behind, so it's helping.
"This role was therapeutic for me because I got a chance to take all of what was going crazy inside of me.
"When you sing, you can just release and yell and go crazy, but this was intense. I had to hold on to it every single day. As Florence, I had to hold it. She couldn't outburst, she had to suffer. She couldn't speak as much, so I got to find out how strong I am."
The fact that she is almost unrecognisable in the film - even fellow cast members didn't realise they were on set with her - was a big help.
"It was best that I disappear," she says. "When I see the film, I'm able to watch it from a critical standpoint and say 'Wow I really lost myself to this character', so it's better that I'm not recognisable at all.
"I've seen a lot of my films. I did Betty And Coretta and I did Rock Of Ages, but the one thing that stood out was I could still see me, Mary J Blige. But this character just possessed the whole thing. She's taken it away from me and I'm happy about that."
The process was aided by the intense workshops she took part in with the film's Oscar-tipped director Dee Rees, which particularly helped her build her relationship with her on-screen husband Hap, played by Stranger Things star Rob Morgan.
"The way she did it, you didn't know it was happening," she says.
"I was caught completely off-guard. You have to find this character right there sitting there, you have to make this person alive.
"When I first walked in for the one with Hap, I'm Mary J Blige and he goes 'There goes my baby' and I'm like 'No I'm Mary J Blige still, I need to sit down and turn into Florence so I can talk to you because I need to be intimate with you'.
"By the time we were done, I had a story about who Hap was and he had a story about who Florence was.
"It was cathartic, therapeutic, because I was able to give so much of my heaviness to Florence. It was kind of a load off.
"I was able to give it to Florence and let her go and be this woman and look at her kids through those eyes of pain and not know what is going to happen from one day to the next... but still loving them and having faith that everything is going to be alright."
Mudbound is released on Netflix and in limited UK cinemas today