"He's always cheerful," his wife Kim Woolen tells PEOPLE

By Melody Chiu
Updated November 12, 2014 05:20 PM
Credit: David Livingston/Getty

After getting diagnosed with Alzheimer’s disease in 2011, Glen Campbell embarked on a tour with more than 150 dates, performing to packed stadiums across the country.

In a new documentary, Glen Campbell: I’ll Be Me (out Nov. 14), fans of the country legend, 78, will get a look at what went on behind the scenes as the performer’s mind degenerated.

“I’m really proud of him to be so courageous, to open up and be vulnerable before the whole world,” the singer’s wife Kim Woolen, 56, told PEOPLE at the premiere Tuesday night in Los Angeles.

Woolen, who appears in the film with the couple’s 27-year-old daughter Ashley, said her most memorable moment from the tour was “see[ing] the kids take a bow along with him and the whole crew. We had been through so much together.”

Though director James Keach was hesitant at first to create the documentary because of the “depressing” subject matter, “the moment he met Dad there was no question about him doing it,” said Ashley. “If you’re around my dad for even five minutes, you’ll get the feeling of joy from him, and he’ll have already told you about five jokes. He just makes everyone feel at ease.”

According to Woolen, Campbell is still “really healthy” physically, but has “lost most of his language skills.” But what he hasn’t lost is his ever-present sense of humor.

“He’s always cheerful. He loves to laugh, and he tells jokes it makes us laugh, and then it brings him joy that he’s made us laugh,” said Woolen.

The family is also embracing Campbell’s rare moments of clarity in their visits with the singer, who now lives at a care facility.

“The other day when I went to visit him, I walked into the room and his face lit up. He walked over to me and gave me a big hug, and whispered in my ear, ‘I remember you,'” shared Ashley. “I didn’t want to ever let go.”

With reporting by REAGAN ALEXANDER