Reality TV star, Jack Osbourne, the son of rocker Ozzy Osbourne, has been diagnosed with multiple sclerosis.

The shocking news comes just after the 26-year-old and his fiancée Lisa Stelly welcomed their daughter Pearl Clementine in April.

"I was just angry and frustrated and kept thinking, 'Why now?'" Jack told People magazine in an interview released on Sunday.

Doctors broke the news to the new father after he lost 60 percent of his vision in his right eye, according to Britain’s Hello! magazine.

"I got really sad for about two days, and after that I realized being angry and upset is not going to do anything at this point — if anything it's only going to make it worse," Jack told Hello! "Adapt and overcome’ is my new motto."

Jack said his fiancée Lisa has been very supportive.

"Jack will have to change his life for the better - get healthier, not get stressed," Lisa told the magazine.

Multiple sclerosis is an autoimmune disease that affects the brain and the nervous system and destroys myelin sheath, protective layers between the nerves in the brain and spinal cord which slows or stops impulses from being carried around the body.

The disease can result in blindness, slurred speech, muscle weakness and loss of coordination, and in severe cases, paralysis.

MS differs in individuals, with some people going through life with only minor problems and others becoming severely disabled. 

There is no known cure for MS, a disease which is two times more common in women than men, and between two and five percent of cases are discovered in children under 16 years of age.

Jack's parents, Sharon and Ozzy, said they were still struggling to come to terms with their son's diagnosis. 

Sharon even blames herself for the diagnosis.

"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," she 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," Ozzy added.

Jack's treatment will consist of a combination of daily drug treatments, holistic therapies and lifestyle changes that are designed to reduce his stress and promote his health.

"Please support my brother @mrjacko in not only his bravery but honesty!" Kelly Osbourne tweeted on Monday morning. "I love you so much jack & I'm so proud of you!"

"Thank you all so much for the kind and inspirational words. It means a lot," Jack had tweeted following the news of his diagnosis.