Jack said he fears for Nick's life if Bobbi Kristina Brown 'doesn't pull through', reported Ace Showbiz.
"It hurts a lot, seeing him in pain," Jack, who is like a father figure to Nick, said after seeing his intervention with Dr Phil.
"Him not wanting to go forward because he's hurt so bad... It's hard for him each day. He doesn't know if he can make it another day. It's getting harder and harder.
"He's out of control right now. He's hurt. He's hitting rock bottom with this," Jack said of Nick who entered rehab after he was unable to continue Dr Phil's interview.
When asked how Nick met Bobbi, Jack said they were neighbours. He also denied that Nick was adopted by Bobbi's mother Whitney Houston.