Ozzy, who has struggled with drug and alcohol addiction for decades, had long worried about history repeating itself. On the family's MTV reality series The Osbournes, he frequently lectured Jack, 17, and Kelly, 18 (Aimee, 19, does not participate in the show), on the evils of drug use. "It ain't gonna lead to anywhere but bad places," he once said. "Look at me." The lesson rubbed off on Jack, who took a break from partying in February after admitting to mom Sharon (then finishing up her chemotherapy treatments for colon cancer) that he was overindulging in marijuana and alcohol. But he fell into old habits during a recent stay at his parents' Malibu beachfront home. Says a family source: "He felt like he was in a fog, and he wanted out."
Jack opted to get treatment after "Sharon and Ozzy encouraged him to take a look at his life and make some changes," says the source. His parents know he made the right decision. "It takes a lot of courage and strength to admit you need help," Ozzy told PEOPLE, "and both Sharon and I are proud Jack is facing his problems head-on."