Sen. John McCain made a huge impact on countless people before his death — especially his 106-year-old mother, Roberta McCain.
A close McCain family friend tells PEOPLE that Roberta is “incredibly proud” of her middle child, the longtime politician and decorated war veteran who lost his battle to stage-four brain cancer at the age of 81 on Saturday.
“Roberta was his biggest supporter and the leader of his fan club. She was incredibly proud of him,” the source says. “His mommy loved him. He knew that.”
As Roberta grieves the loss of her son, the source points out that she “is a very strong woman,” noting the centenarian’s age as proof.
“She is all there, mentally, and is still going strong at 106,” the friend tells PEOPLE. “She outlived her 81-year-old son. That tells you a lot. But it’s a tough blow to bury your child.”
The insider adds that while Roberta did not travel to Arizona following Friday’s news that her son would be ceasing medical treatment for glioblastoma — the most aggressive form of brain cancer, with which he was diagnosed in July 2017 — the two did speak on the phone recently, and she knew the extent of Sen. McCain’s illness.
“I can only imagine what she’s going through,” the friend says of Roberta through tears.
The source tells PEOPLE that Roberta and Sen. McCain’s first wife Carol still keep in touch and have frequent conversations. (The two divorced in 1980 after 15 years of marriage and share three children: sons Douglas and Andy and daughter Sidney.)
“John never stopped loving Carol,” the insider says, adding that the exes spoke regularly before Sen. McCain’s death.
A close family friend revealed exclusively to PEOPLE on Friday, “Roberta is 106, but she’s spunky. She knows he is ill.”
RELATED VIDEO: Senator John McCain Dies at Age 81
Roberta has been a vocal supporter of her son’s political efforts over the years. At 96 years old, during Sen. McCain’s 2008 presidential campaign, she gave a speech to campaign workers, captured by CSPAN.
“Johnny is going to be the president of the United States and he’s going to keep the traditions … and the standards high,” she told the crowd, receiving applause.
“All we want is a world where we can raise our children, have a chance at prosperity and happiness, and we can vote any way we want to,” she continued before ending on a sweet note. “I can’t thank you enough … I wish I could kiss each one of you on the cheek. If I get a chance, I will.”
PEOPLE spent time on with Roberta on Sen. McCain’s campaign bus during his presidential campaign in 2007. At one point, Roberta, then 95, teased her son, “I want to correct you when you start telling all those big lies.”
When the conversation turned to the “Straight Talk Express” campaign bus itself — “This is wonderful! Can you imagine me comfortable on a bus?” Roberta said — Sen. McCain asked his mother to regale the group with a story about a driving mishap in Arizona.
“It’s so dumb!” she began. “I was driving across the continent [in 2003] and had 300 miles to Los Angeles. I thought, well, I can make it tonight. So I put the gas on. I got a ticket for driving 112 miles per hour, signed my name and went on my way.”
When her granddaughter Meghan McCain, then 23, praised her for the tale, Roberta responded, “Honey, I shoot my mouth off like a neophyte!”
Roberta spoke earnestly about her son, too, during the interview. “I think civilization depends on this election,” she told PEOPLE. “Johnny should have been dead 10 times already. Not just when he was a POW in Vietnam. He had so many near-misses [as a naval aviator]. He was saved for some reason.”
In an emotional tweet following Sen. McCain’s death, his wife Cindy, 64, wrote, “My heart is broken. I am so lucky to have lived the adventure of loving this incredible man for 38 years. He passed the way he lived, on his own terms, surrounded by the people he loved, in the place he loved best.”
His daughter Meghan McCain was among the people praising Sen. McCain on social media in the wake of his death. “In the thirty-three years we shared together, he raised me, taught me, corrected me, comforted me, encouraged me, and supported me in all things,” she wrote in part.
Meghan added, “He taught me how to live. His love and his care, ever present, always unfailing, took me from a girl to a woman — and he showed me what it is to be a man.”