Kelly Osbourne is mourning the death of her dad and rock legend Ozzy. On Thursday, the musician and daughter of the Black Sabbath frontman returned to social media for the first time, using the opening line to “Changes.” “I feel unhappy,” she wrote. “I am so sad. I lost the best friend I ever had.”

Ozzy and Kelly - whom the heavy metal pioneer shared with wife Sharon, along with daughter Aimee and son Jack - were close. Fans first got a look at their family dynamic on The Osbournes, a reality show that ran on MTV for three years in the early 2000s.