Glen Campbell and his wife, Kim Woolen, in 2011
More than three years into his battle with Alzheimer's
, Glen Campbell can no longer do what's been second nature for him for most of his life – perform.
When asked if the country great would ever play for an audience again, his wife, Kim Woolen, 55, says it's unlikely.
"He can't even tune a guitar now. If I tune one and hand it to him he can still play, [but] not like he used to," Woolen told PEOPLE at the Open Hearts Foundation's 4th Annual Gala in Malibu on Saturday. However, he can still "play a couple licks here and there, and he finds joy in that."
Now living in a memory-care facility
near their Nashville home, the "Rhinestone Cowboy" singer, 78, spends his days looking at pictures and chatting with Woolen, who visits him "every single day for hours."
"It's a very nurturing place … [and] he feels secure there," she says. "I sit with him through his meals … we hug each other and cuddle. I savor every day."
And though it's been "absolutely heartbreaking" for the Campbell family (the couple have three children together), they've tried to stay positive.
"There's a lot of sadness, [but] we just continue to try to make the best of every day and keep a sense of humor," says Woolen.
Reporting by MATTHEW COLE WEISS