Ozzy Osbourne and his wife Sharon are reeling after their TV daredevil son Jack was diagnosed with multiple sclerosis (MS).
The 26-year-old - who has recently become a father - was found to have the incurable autoimmune disease after a frightening spell in which he lost 60% of the vision in his right eye.
He and his family have revealed his condition in an interview with Hello! magazine in which Jack said he had experienced a range of emotions.
"While I was waiting for the final results, I got really, really angry," he said. "Then I got really sad for about two days, and after that I realised, being angry and upset is not going to do anything at this point - if anything it's only going to make it worse. 'Adapt and overcome' is my new motto."
He has spoken out to raise awareness of the condition and the support of his fiancée Lisa Stelly - who gave birth to baby Pearl two months ago - is helping him to keep a positive outlook.
Jack Osbourne and fiancée Lisa Stelly
Jack went for tests at the same hospital his daughter Pearl had been born just three weeks earlier. The condition affects the brain and the nervous system.
He said: "The timing was so bad. I'd just had a baby, work was going great - I kept thinking, 'Why now?'"
Black Sabbath star Ozzy and former X Factor judge Sharon have also been stunned and are still struggling to come to terms with their son's condition, which was confirmed by a neurologist last month.
Sharon said she has been questioning whether she is to blame. She added: "I keep thinking, 'what did I do wrong? What did I eat or drink when I was pregnant?' I feel like it's somehow my fault."
Ozzy said: "If it was me, you'd think: 'Ozzy had a reputation and it caught up with him', but Jack is such a good guy."
Jack - an extreme sports enthusiast - will use a combination of daily drug treatments, holistic therapies and lifestyle changes.
His fiancée said: "Jack will have to change his life for the better - get healthier, not get stressed."
:: The full interview is in the new edition of Hello! magazine which is out now.