Jack Osbourne‘s tearfully remembering a moment he and his late father, Ozzy Osbourne, shared a couple of weeks before his death … and he says, in hindsight, it couldn’t have been more perfect.

Ozzy’s youngest child got emotional Monday on ‘GMA,’ when he opened up about the pain of losing a parent. He also talked about how his mom, Sharon, is handling life without Ozzy … saying, she’s “okay, but she’s not okay.”

Jack started choking up when he talked about Ozzy being clean, sober and in “such a good mood” at the end of his life … even though the late rocker once said, “If I were clean and sober, I wouldn’t be Ozzy.”

During Ozzy’s final performance — the July 5 tribute concert — Jack reveals he took a moment backstage to run back to the dressing room, and give his dad a big hug and kiss … crying and telling him to “crush it.”

Jack ends the interview describing his dad’s last show as kind of a “living wake” … he got to say goodbye to everyone — and wanted to be remembered as a guy who loved his job, and family.

As you know, Ozzy died July 22, and his family told us he was “surrounded by love” when he passed.