Kelly Osbourne regards Lady Gaga as "a great big hypocrite".
The Fashion Police TV presenter and the Born This Way singer engaged in a Twitter feud last year.
The hostility arose after Kelly poked fun of Gaga for wearing a burka at London Fashion Week during an appearance on UK television show Alan Carr: Chatty Man.
Gaga's fans inundated Kelly with cruel taunts and death threats. Kelly's mother Sharon got involved and wrote Gaga's manager an email asking him to step in.
Gaga responded with her open letter to Kelly, calling for her to be a better role model and blaming her for "breeding negativity" on Fashion Police.
Kelly reveals her view of Gaga remains unfavourable following the conflict.
"I loved Lady Gaga. I totally believed in everything she stood for, until I realised she's a great big hypocrite. Don't say, 'When you see bullying, intervene,' while letting your fans send me death threats. If my fans did that, I would not stand for it," she told the June issue of Cosmopolitan magazine.
Gaga is the founder of the Born This Way Foundation, an anti-bullying charity.
Kelly is convinced the musician is fuelled by self-interest.
"You can say whatever you want with your millions of monsters. I know the truth," Kelly said.
"Your bells and whistles mean nothing to me. You're feeding on the freaks and geeks to further your career? Do you really care about the gay community? Because if you did, you'd stand up for it more than you do."