Whitney Houston's sister-in-law Pat Houston delves into details of ‘Whitney' documentary

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The first voice you hear in the opening moments of “Whitney,” the searing documentary about the late supernova, is the singer herself.

"I would look up to God (and ask), 'Why is this happening to me?'" she says, a haunting recollection given how her life would unfold until her untimely death in 2012.

The two-hour film, which opens Friday, is the first biopic fully sanctioned by Houston's family.

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Brothers Gary and Michael, mother Cissy, sister-in-law Pat (also an executive producer of the film), ex-husband Bobby Brown and a cast of close friends and professional contacts all contribute candid commentary under the skillful interviewing of Oscar-winning director Kevin Macdonald.

While there is an unshakable sadness that permeates “Whitney” — which culminates with Houston’s drowning in a bathtub on the eve of the Grammy Awards — Macdonald strives to remind us of the reasons why Houston became one of the best-selling female artists in music history, with more than 200 million albums sold worldwide.