*The National Enquirer cites sources who say Whitney Houston spends over $300,000 a year on drugs – and friends believe she’s back in a downward spiral that will soon take her life.

Her entourage recruited a drug dealer who sold her $6,000 worth of cocaine during a tour stop in Europe in June – this, according to “an eyewitness to the deal,” the tabloid reports.

The same source adds that Whitney, 46, was high as a kite during her interview with Oprah Winfrey, despite telling the talk show host that she was drug-free.

The Enquirer says their own “in-depth investigation” has discovered that Whitney has spent an average of $6,300 a week on drugs – or a staggering $327,600 a year.

“Whitney is a dead woman walking! With the amount of drugs she’s buying, she won’t be able to live long. She’ll be dead in months,” her friend Marlon David, a party promoter, told The Enquirer.

“A friend of mine… is a drug dealer who deals in cocaine. One of Whitney’s people called him and said, ‘Whitney wants to party,'” David told The Enquirer exclusively.

The Grammy-winning singer’s sobriety came into question almost as soon as she kicked off her “Nothing But Love” comeback tour in February in South Korea. Throughout the trek, Whitney was seen in multiple YouTube clips struggling hard to hit notes.