Whitney Houston was the victim of sexual abuse as a child, and the abuser was her cousin and singing star Dee Dee Warwick, the sister of Dionne Warwick, said Mary Jones, Houston's aunt, according to a new documentary.

» Who was Dee Dee Warwick? Singer accused of sexually abusing Whitney Houston

"Whitney," by Kevin Macdonald, debuted at the Cannes Film Festival in France on Wednesday.

» Rare footage shows Whitney Houston rehearsing 'I'm Your Baby Tonight'

Gary Houston, a former NBA player and Houston's brother, tipped Macdonald off about the abuse.

"Gary the brother told me he was abused by Dee Dee," Macdonald told IndieWire. "So it's not allegations. He's saying I was abused by this person and told me, 'I think she abused Whitney.' Pat Houston (Gary's wife), who's here, told me that, yeah, Whitney had told her this but not given any details."

"For about two months, that was all I had. Then Mary Jones, who was her assistant for a long time and was with her every day for the last 10 years of her life, decided she wanted to talk about it."

Dee Dee Warwick, whose hits included "You're No Good," battled drug addiction for much of her life. She died in 2008 at the age of 63.

» First trailer for estate-approved Whitney Houston documentary released

"Whitney," approved by the Houston estate, details Houston's alleged affair with longtime companion Robyn Crawford, as well as her battles with drug addiction. Houston's hits included "I Will Always Love You," "Saving All My Love For You," "I Wanna Dance with Somebody (Who Loves Me)," "How Will I Know" and "Greatest Love of All."

Houston, 48, was found dead in a hotel bathtub on Feb. 11, 2012, in Beverly Hills, California, on the eve of that year's Grammy Awards. Heart disease and cocaine use were listed as contributing factors in her death.

Houston's daughter with husband Bobby Brown, Bobbi Kristina, died in 2015 at the age of 22 in an Atlanta-area hospice six months after she was found unresponsive in a bathtub at her Georgia home in circumstances similar to her mom's passing.

» Whitney Houston's daughter, Bobbi Kristina Brown, dies at age 22

Houston was a native of Newark, and she lived in Mendham after she became a star. The movie comes out July 6 in the United States.