Whitney took Nick Gordon under her care over a decade ago after learning his birth mother was no longer able to care for him, and raised him alongside Bobbi Kristina "like a son".
"YES, me and Nick are engaged," Bobbi Kristina posted on Facebook yesterday.
"I'm tired of hearing people say 'Eww you're engaged to your brother' or 'If Whitney was still alive would we be together' or 'Would she approve of this.'
"Let me clear up something, we aren't even real brother and sister nor is he my adoptive brother. My mom never adopted him.
"In fact, mommy was the one who even said she knew that we were going to start dating."
Daughter of a legend: Bobbi Kristina hit back at critics suggesting Whitney wouldn't approve of her engagement
Engagement rumours started swirling last year when the pair were seen together in the trailer for reality show The Houstons: On Our Own.
"People need to seriously stop judging my relationship. Pretty sure it's my own decision who I want to be with," she continued.
"Yes, my relationship may not be perfect. We will have rough
patches, just like every other relationship. And we have had our rough
patches.
"You may or may not agree with my relationship. You may or may not respect it. Judge me, go ahead. Your opinions are yours and mine are mine.
"It is my life and not yours. The decisions I make have nothing to do with you. Goodnight."