"There were always a lot of secrets," he confesses. "If you don't resolve things and you don't deal with things, they never go away."
But Oscar-winning director Kevin Macdonald didn't discover the biggest secret of all — that both Whitney and Gary were allegedly molested by their late cousin, singer Dee Dee Warwick (sister of Dionne), when they were kids — until the 11th hour of making the film last fall. "I was just coming to the end of the edit," Macdonald tells The Post. "We had worked on it for about 18 months, and then we heard this bombshell, which redefined the whole thing."
This revelation gave the documentary — which opens in theaters Friday after premiering at the Cannes Film Festival in May — another tragic turn in Houston's tale, which ended in 2012 when the 48-year-old singer accidentally drowned in her hotel room bathtub. (Cocaine use and heart disease were listed as contributing factors.) But in addition to taking a hard look at everything from her childhood trauma to her drug addiction, Macdonald also wanted to celebrate Houston as "one of the great artists of the late 20th century."