"I can't even breath right my now. I'm crying so hard," Osbourne, 26, tweeted. "I just lost one of my best friends. I love you forever Amy and will never forget the real you!"
When one Twitter user accused Osbourne of not doing enough to help Winehouse overcome her addiction issues, the E! personality fired back: "Are you f***ing kidding me? You have no idea what you are talking about! It would be in your best interest to shut the f*** up!"
(With the help of Winehouse's father, Osbourne famously helped the troubled singer check into rehab in 2008).
"I miss my friend," Osbourne added. "I'm going to be off Twitter for awhile. Thank you for all your support!"
On Saturday, police found Winehouse lifeless in her Camden Square apartment. Pronounced dead on the scene, Metropolitan Police told Us Weekly in a statement that "the circumstances of the death . . . are being treated as unexplained."
Winehouse is is survived by her parents, Mitchell and Janis, her older brother, Alex.