Bobbi Kristina Brown engaged to Nick Gordon

Whitney Houston's daughter, Bobbi Kristina Brown, has confirmed her engagement to Nick Gordon -- whom Houston took in as a child and raised as an unofficial adoptive son.

In a promotional clip for "The Houstons: On Our Own," Lifetime's upcoming reality show about the singer's family, Brown, 19, giggles, "We're engaged" in a voice-over.

The promo shows Houston's brother, Gary, telling Gordon, 22, "No one knew that from a godson you would turn into a boyfriend," to which Gordon replies, "Nobody has to be in my business."

Pat Houston, Gary's wife and Whitney's manager and close friend, announces at another point, "Engagement? This is unacceptable."

Gordon then tells the camera, "The family has me out to be a bad person," while the clip ends with Brown, likewise to the camera, saying, "They want to see us fail. I got one thing to say: You won't."

Speculation about a romance between Brown and her childhood companion has swirled since March, when Brown was photographed strolling with Gordon and wearing a large, silver-colored ring that suggested a possible engagement.

Gordon responded at the time by tweeting, "Wow you can't believe anything the media says. First time I heard any of this."

Brown is the daughter of the six-time Grammy-winner -- who died Feb. 11 at 48 in an accidental drowning due to the effects of cocaine and heart disease, the Los Angeles County coroner's office determined -- and R&B singer Bobby Brown, who divorced in 2007.

Houston's brother Michael told ABC News in March Gordon was "like a son" to Houston.