United Kingdom, Aug. 6 -- Jack Osbourne's heart is "full of so much sadness" following the death of his dad Ozzy Osbourne.

The Black Sabbath star died on July 22 - just two weeks after he reunited with his bandmates for a huge reunion show in his hometown of Birmingham - and the tragedy left his son Jack, 39, totally devastated.

He's now shared a poignant tribute to Ozzy and insisted he feels "lucky and blessed" to have him as his father. In a post on Instagram , Jack wrote: "I haven't really wanted to post anything since the passing of my father. My heart has hurt too much.

"I'm gonna keep this short because he certainly hated long rambling speeches. He was so many things to so many people, but I was so lucky and blessed to be apart o...