It seems Jack Osbourne got more out of his two months of treatment at a Pasadena, Calif., rehab facility than he expected.

"I went in there with the mentality of 'I'll do my time. I'm just going to get out of here and I'll be fine. Give it a week or two and I'll be back to square one.' But I did a lot of soul-searching," Osbourne, 17, told MTV News. Excerpts from the exclusive interview are posted on the MTV News Web site; the network, which also airs his family's series, "The Osbournes," will broadcast it Tuesday night.

Last week, the network reported that Osbourne had admitted to an addiction to the controversial painkiller OxyContin. During the rehab process, he says, he learned "all this stuff you don't really know about your character, like who you really are. ... For so long, you just don't know because you're so full of chemicals and stuff. You just get thrown off.

"I have a tendency to really stuff things -- like, I don't really express certain feelings," he added.

Issues that Osbourne had to face, he says, were his sudden fame and his mother's cancer. "That sh-- hurt a lot, and I was constantly just drowning it," he says, revealing, too, that he began drinking at age 13 and in the past two years was adding Vicodin, Valium, Xanax, Dilaudid, Lorcet, Lortab, Percocet, marijuana and Oxy to the mix, according to MTV.

At the time Osbourne checked into Las Encinas Hospital three months ago, Jack was described by the family spokesperson as having "an undisclosed addiction." He was released from the facility on June 18.