The soap star confirmed her living situation on Twitter, saying that she's had a tough year and had "lost" her home.
"I have the love of my kids and a few good friends," she said.
She last appeared in the BBC One soap in 2010, playing the role of Sam Mitchell.
Ms Westbrook says she spoke out because someone was trying to sell a story about it to a magazine.
The 41-year-old first appeared on Albert Square in 1990 but left in 1996. She had a brief second stint in the show between 1999 and 2000.
In 2002, she was replaced in the role by another actress, Kim Medcalf, who left EastEnders in 2005. Ms Westbrook then returned to the role in 2009.
Ms Westbrook has previously dealt with cocaine addiction.
She was one of the contestants in I'm a Celebrity... Get Me Out Of Here! in 2003 but left the competition because she feared it was interfering with her recovery.
"I was living hour to hour in a world of hurt and thought, 'I've got to go to an AA meeting and centre myself'," she said in a later interview.
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Hollywood actress Glenn Close stars in the musical, which opened on Monday evening at London's Coliseum theatre.
Writing in The Guardian, Michael Billington said the new production had given the show "a new lease of life".
"Close delivers the big lines not with a camp flourish but as if they were sincerely felt," he said.
Billington noted that the show had "none of the epic scale of the original London production" but added this was to the producers' credit: "Sometimes semi-staged is better than the luxurious grandeur of an elephantine West End musical."
Glenn Close is reprising the role of Norma Desmond, a character she first played in Los Angeles in 1993. She won a Tony award for her Broadway performance in 1995.
Holly Williams from theatre website WhatsOnStage said: "It might be 20 years since she bagged a Tony in this part, but I wouldn't bet against her scooping a few shiny new gongs this time round."
However, some critics did note that Close's voice occasionally struggled with the higher notes.
"[Close's] vocal instrument may not be as sharp as it once was, but she brings an utterly ferocious intensity to the part and the songs," Mark Shenton wrote in his review for The Stage.
Time Out also had some criticisms of the production: "Like many later Andrew Lloyd Webber musicals, Sunset Boulevard is not brilliant."
Andrzej Lukowski added that "69-year-old Close is definitely a bit old to play 50-year-old silent movie star Norma Desmond".
Rod McPhee, writing in The Daily Mirror, said Close "masterfully belts out the show's biggest numbers, and earned rapturous applause as a result. Her first musical in London's West End proves that she's far from a fading star."
Sunset Boulevard tells the story of a Hollywood writer named Joe (played in the new production by Michael Xavier), who is being chased by mob creditors.
Joe seeks refuge in a Los Angeles mansion, only to discover it is already being inhabited by Norma Desmond, a wealthy but forgotten silent movie star.
Culture minister Ed Vaizey attended Monday evening's performance, tweeting: "Absolutely wonderful. Glenn Close gives the performance of a lifetime. One of the best things I have seen."
Speaking to the BBC after she came off stage on Monday evening, Close said: "Norma Desmond is one of the best parts ever written for a woman."
"It's a phenomenal show, it's such an exciting journey and it has been the best adventure. I feel so lucky. I am on such an emotional high, I've never had this kind of response."
Danniella Westbrook, who is best known for her role in EastEnders, has confirmed she is homeless, living in "sheltered housing".
[NEXT_CONCEPT]
A new production of the Andrew Lloyd Webber musical Sunset Boulevard has received a positive response from critics.