"We told him about the GRAMMY," Glen's wife Kim told ET. "He might have forgotten it immediately. He knew something good happened."
The five-time GRAMMY winner was diagnosed with Alzheimer's in 2011. The disease has robbed him of his memories, but he's held on to the ability to sing.
"[The song] is a little dark," Kim said. "It definitely made me tear up."
"I'm Not Gonna Miss You" is featured in the documentary I'll Be Me, which followed Campbell on his farewell tour in the U.S., Australia and Europe as he battled Alzheimer's. The song was co-written by Campbell's longtime friend and producer Julian Raymond.
"He said to me the funniest thing," Julian told ET. "He said, 'I don't know what everybody's going on about all this stuff for because it's not like I'm going to miss anybody.' He always finds the humor in something."
Kim added that while Glen's memories are fading, he hasn't forgotten everything.
"He still knows who I am and we kiss and cuddle," Kim said. "And I know he knows who I am because of the way he kisses me. We still love each other very much."