Even in her final days, Betty White knew she was adored by her fans, according to her agent at APA and longtime friend Jeff Witjas.

Speaking with PEOPLE after her passing at the age of 99 on Friday, Witjas opened up about his relationship with the late star, as well as how White appreciated the love she received from around the world.

"She knew it, but I would often remind her," Witjas said. "Even when she wasn't working, I would say, 'Betty, millions of people out there still want you. You're receiving fan letters, and I'm getting offers for you.'"

"I'm not sure if she fully embraced it or truly understood the extent of it," he continued.

"I always made it a point to reinforce it because I believed she should know. I never wanted her to think that the world had forgotten about her while she was at home. That was not the case."

"Betty lived a wonderful life, a life of her choosing. She was happy," Witjas added. "Each time I told her, 'Betty, you are loved,' she'd give me a sly smile and say, 'Really?' I hope she knew. I believe she did. It was more than love."

Witjas, who previously confirmed that the actress "passed away peacefully in her sleep," had a close bond with the Golden Girls star, considering her not only a client, but also a dear friend.

"She was an incredible lady. It's difficult to put into words," he said. "We had a special relationship that went beyond a typical professional one."

"We became really good friends, and we always laughed, no matter what we were doing. She was always positive and had a sunny outlook," Witjas continued. "She promised me she would make it to 100, and she almost did."

Speaking further about White, Witjas shared that the iconic star spent most of her final years at her home in Los Angeles.

"She mostly stayed at home during her final years.

She didn't go out. She was under a doctor's care, not because of any particular reason, but just being cautious due to COVID," he said.

"I know there was a period where she responded to all the fan letters," he added, but that eventually slowed down. "I think she just didn't have the energy to respond like she used to. She read them; she just lived her life. She was comfortable at home."

Witjas also revealed that he and White discussed her upcoming 100th birthday.

"We joked about it. I told her, 'Betty, we know you're going to turn 100. Let's start focusing on 101.' That's how we kidded around," he shared.

"She never made a big deal out of it."

"That's a pretty big number," she once told him. "But we didn't sit there and say, 'Betty, how did you do it? What's your secret?'" Witjas explained, mentioning that she often joked about her diet.

Witjas also noted that White was aware of her advanced age and made the choice not to get another golden retriever after her beloved pet Pontiac passed away a few years ago.

"I asked her if she wanted another pet, and she said she would prefer not to because she believed that if she got a puppy or went to a shelter, the dog would outlive her," he said. "I would tease her, saying, 'Betty, you're outliving everyone. You're not going anywhere.' But she was very sensitive towards animals."

"Her work speaks for itself," Witjas concluded, joining millions around the world in mourning the loss of Betty White. "Her legacy was sealed. It was sealed years ago."