By the end of her life, Whitney Houston had thrown away every last scrap of the poise and beauty that had made her the ultimate diva of her generation.

Leaving a Hollywood nightclub two days before her death, Whitney Houston was drenched in sweat and disoriented a wad of mint chewing gum visible in her gaping mouth.

Blood from a cut trickled down her leg, but the singer herself, surrounded by party-loving hangers-on, didn’t seem to notice.

Alternately waving and cursing, this was not the Whitney Houston who conquered the world – a church-going supermodel with a once-in-a-generation voice of exceptional power and sweetness.

This was a woman who, despite at least three attempts at rehab in the past eight years, appeared fully in the grip of drug addiction: wired, wrecked and out of control. Inside the club, it is claimed, Whitney Houston nearly came to blows with a partygoer who she felt had “got into her face”.

So why could nobody save Whitney Houston? In truth, having spent almost two decades destroying herself, she was past saving.

Her voice, with her signature, high-octave power note, had been pitifully diminished by years of abuse, particularly the smoking of crack cocaine. The soaring vocals had become a soft, whispery falsetto.

“She doesn’t want to come, my soprano friend,” Whitney Houston told a booing concert audience in London in 2010.

The years of material plenty were behind her, too. Whitney Houston was reportedly once again “flat broke”, even though she should have had a fortune well in excess of $160 million.

Indeed, despite earning up to $30 million with a colossal 50-date global tour only two years ago, she was reportedly this month reduced to asking her great benefactor, Clive Davis, the music mogul who “discovered” her, for hand-outs yet again.

Whitney Houston’s home in New Jersey was said to be in danger of being repossessed. Another home in Atlanta already had been.

The legendary singer was partying at the Beverly Hilton only because she was on someone else’s tab: the record label was paying for her to be with them in the run-up to last night’s Grammy awards.

There were hopes of yet another album from Whitney Houston, despite the relatively poor performance of her comeback in 2009, and she had recently been in the studio. She had also finished making a film, Sparkle, a showbiz saga about a trio of singers, which Sony has announced will still be released in August.

Whitney Houston’s most recent romantic partner was a 31-year-old rapper, Ray J, who is chiefly famous for being the man in a homemade sex tape shot in 2003, which made reality star Kim Kardashian famous.

Ray-J is also the cousin of rapper and drug advocate Snoop Dogg, so he was not the kind who might have been counted on to keep her on the straight and narrow.

Whitney Houston and Ray-J had an on-and-off four-year liaison, which her fans felt had depressing echoes of her mutually destructive marriage to “bad boy” rapper Bobby Brown, who she divorced in 2007.

Whitney Houston pictured in 2006, sick and haggard

Whitney Elizabeth Houston was born in 1963 in Newark, New Jersey, and her mother was the successful gospel singer, Cissy Houston. Her cousin was Dionne Warwick and Aretha Franklin was her godmother.

Known as Nippy as a child, Whitney Houston was the youngest of three children. Her mother divorced John Houston, an Army serviceman, but Whitney remained close to both parents.

They supported her in her dreams of stardom – a fact she later said accounted for her enormous self-confidence.

From the age of five Whitney Houston would sing in the choir at the All Hope Baptist church in Newark, where the family worshipped.

As a teenager, Whitney Houston started to get involved in the music business. Aged 15, she sang backing vocals on the Chaka Khan hit I’m Every Woman.

Clive Davis of Arista records first laid eyes on her in 1983, when she was 20, and was bowled over.

Her first album, Whitney Houston, was released two years later, yielding the No 1 hits The Greatest Love Of All, How Will I Know and Saving All My Love For You. It remains the best-selling debut album by a female artist in music history.

Her second album, Whitney, released in 1987, included the hits I Wanna Dance With Somebody and Where Do Broken Hearts Go. It sold 25 million copies worldwide.

Whitney Houston would often travel with her mother. Also always present was her “executive assistant” Robyn Conway, her best friend at school, who she said was “like a sister” to her. She put Robyn Conway on her payroll, but was she something more?

Whitney Houston always denied the persistent rumors she was bisexual, and claimed people got the wrong impression only because she didn’t start dating until she was in her late 20’s.

In 1989, Whitney Houston met Bobby Brown at a music awards show, and they married in 1992. Daughter Bobbi Kristina was born a year later.

Whitney Houston was at the peak of her fame, thanks to the film The Bodyguard and the colossal cover version I Will Always Love You.

But outside the spotlight, her life was far from perfect. Whitney Houston and Bobby Brown had settled in a huge mansion in New Jersey, complete with a pool and recording studio, but the marriage was not happy. He was accused of domestic violence against her in 1993. Whitney Houston said he had slapped her during a jealous argument.

In his autobiography, Bobby Brown hints she deceived him about her true sexual orientation and that their marriage was designed to cover up her bisexuality.

“I realize Whitney had a different agenda than I did when we got married,” Bobby Brown said in his book. “I believe her agenda was to clean up her image; mine was to be loved and to have children.”

Talk of her impossible behavior began to circulate as Whitney Houston started failing to turn up to events, including a celebration of the career of her mentor, Clive Davis.

Whitney Houston admitted in a recent interview that she would take cocaine “every day” in the mid-Nineties.

The singer became skeletally thin and appeared disoriented at times. She was fired from a slot on the Oscars ceremony in 2000 after singing the wrong song at rehearsals.

Later that year, Whitney Houston and Bobby Brown were found to be carrying marijuana on a trip to Hawaii.

In 2002, Whitney Houston gave a notorious interview in which she denied taking crack, on the grounds that it was “too cheap” a drug for her.

“We don’t take crack. Crack is whack,” Whitney Houston said. Nobody was very convinced by her denial.

Clive Davis tried to get her into rehab in 2004, with an ultimatum that they could not work together again if she didn’t clean up.

In 2005, Whitney Houston’ sister-in-law leaked pictures to the Press of her bathroom in Atlanta – a sordid, dirty space covered with crack pipes and other drug paraphernalia – to try to shock her into sobriety.

In 2005, Whitney Houston’ sister-in-law leaked pictures to the Press of her bathroom in Atlanta, a sordid, dirty space covered with crack pipes and other drug paraphernalia

In 2006, Clive Davis tried again. Whitney Houston recalled in an interview: “Clive called me one day and said: <<OK, are you ready now? I’m tired of seeing what I’m seeing. I want you back.>>”

In denial about her problems, Whitney Houston said she resisted because she was happy being a mum to Bobbi Kristina. Finally, though, Clive Davis persuaded her that she needed to conquer her addictions and attempt a professional comeback.

The singer Courtney Love had told Clive Davis that the one person who could help Whitney Houston was a former addict named Warren Boyd.

Fabled in Hollywood as the person who got actor Robert Downey Jr. off drugs, his view is that addicts need to have a sober coach to live with them 24/7.

After residential rehab for several months in Pennsylvania, Warren Boyd “secured the perimeter” around Whitney Houston, relocating her to a rented beachside shack in Laguna, Los Angeles, and keeping her away from family and friends – and dealers – in New Jersey for months at a time.

Eventually, Whitney Houston felt strong enough to end her marriage to Bobby Brown. It had been the unhappiest of unions, raven by jealousy and drug use. They were divorced in 2007.

Whitney Houston said she and Bobby Brown started doing drugs together daily around the time of The Bodyguard film, and that Brown couldn’t handle her stardom.

“I think somewhere inside, something happens to a man when a woman has that much control or that much fame.”

Whitney Houston also said that he was unfaithful. “The only thing I did was the drugs. He was too promiscuous, dragging dirt into my home. It disturbed me.”

Getting her off drugs cost more than $1,300 a day for three years – the bill being picked up by Clive Davis. He also paid off a $1.2 million debt on her home.

The debt was pretty extraordinary given that Whitney Houston had sold more than 140 million albums worldwide by then. In the event, the subsequent album, I Look To You, was a damp squib. Released in 2009, her five-octave vocal register was gone thanks to smoking and crack use.

And when she launched the album at a hotel in London, it appeared that without the help of Warren Boyd she had fallen back into her old ways. A nugget of what seemed to be crack cocaine fell from one of her pockets.

There were repeated problems on the tour. Whitney Houston couldn’t hit the high notes and seemed to struggle even to chat with the audience. High-profile promotional gigs – singing on TV chat shows – revealed her ragged form.

And there were still plenty of signs of her infamous temperament. She wouldn’t film in the mornings, and refused all offers of live televised interviews. Clive Davis called her “the most impossible person” he had ever worked with.

Whitney Houston said repeatedly that her teenage daughter Bobbi Kristina helped her to sobriety. In 2009, she said: “She was with me every step of the way.” But the truth seems rather darker.

Her daughter, Bobbi Kristina Brown, now 19, was pictured last year snorting lines of cocaine at a party, smoking joints and drinking beer.

A former boyfriend told the National Enquirer magazine: “Krissi is addicted to cocaine. I’ve tried to stop her, but all she said was: <<I’m just like my mother!>>

“It was difficult to stop her from buying alcohol and drugs because her mother gave her $1,000 a week.”

Last May, Whitney Houston entered rehab for one final time. Sadly, it appears not to have worked. She was out of control on an airplane to Houston in the autumn, when she narrowly avoided arrest after refusing to buckle her seatbelt.

It seems that despite global fame and a constantly supportive family, nothing was enough to keep her clean.

“I have a mother who is very strong and a family that surround me and constantly tell me they love me. And my daughter is my greatest inspiration. She loves me,” Whitney Houston said in an interview earlier this year.