Billy Watson is a grieving member of Whitney Houston's extended family. He's both the brother of Patricia Houston, the late singer's sister-in-law, as well as Ray Watson, the star's longtime bodyguard, who discovered her body in the bathtub at the Beverly Hilton Saturday, where she was pronounced dead at age 48.

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Billy last spent time with the "So Emotional" singer New Year's Eve at a small family gathering in Alpharetta, Georgia, and spoke with her over Super Bowl weekend -- and now that she's gone, he worries for Bobbi Kristina, Houston's 18-year-old daughter with ex-husband Bobby Brown.

Now with her father and other relatives in L.A., Bobbi was released from Cedars-Sinai Medical Center on Sunday.

VIDEO: Whitney Houston, 1963-2012

"Everything [was] stressful," Billy explained to Us Weekly. "Her mama died, so she broke down. Nobody expected her to pass as quickly as she did. [Bobbi Kristina] had a nervous breakdown."

Bobbi Kristina is "OK now," Watson added. "She's alright."

While early reports suggested that Houston may have accidentally drowned, sources tell TMZ that Houston's true cause of death was a lethal combination of Xanax and other prescription drugs mixed with alcohol.

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Billy also confirmed that his brother Ray, Houston's longtime bodyguard is "the one who found her." Following that traumatic discovery, Ray is "OK," Billy said. "He's been with her for 14, 15 years."

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