But on March 26, the 58-year-old grandmother received shocking news – she was diagnosed with acute lymphoblastic leukemia, and doctors informed her she could not travel for her son's wedding.
But her devoted son wasn't going to let anything stand in the way of his mother seeing him say his "I dos."
"I was just so sick and I didn't know what was happening to me. The oncologist came in and said, "Mrs. Holm, I think you have leukemia,' " Catherine tells PEOPLE of her diagnosis. "I was in shock. They moved me to Stony Brook University Hospital the day after Easter."
When doctors told Catherine – who is currently awaiting a bone marrow transplant – that flying could compromise her immune system, the caring staff at the hospital joined forces with her son, Mark Holm Jr. and his fiancée, Joanna, to plan the perfect wedding.
"My daughter-in-law wanted to see if they could hold something there in the chapel, so I could be part of something," Catherine says. "When everybody here heard about it, they were just willing to do whatever to make something happen here for us. It was so wonderful, it was so thoughtful of them. Nobody has ever done anything like that for us. It was very touching for me and my family."
Stony Brook even provided a pastry chef for the wedding, Mark tells PEOPLE. And a fellow leukemia patient took care of all the decorations, while hospital staff set up another room for the reception.
"The hospital did everything," Joanna tells PEOPLE. "They didn't ask any questions. They took care of everything."
Close family members gathered together at the hospital on April 18 for the emotional wedding ceremony.
"It just brought us all together," Catherine adds. "That's all that mattered to me – that we were all together."
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The hospital wedding also gave Catherine the chance to wear the gorgeous dress she bought for the wedding.
"I was so excited – I was going to be able to see them have a ceremony and to wear my gown that I had picked out when I first started getting sick," Catherine says. "I was happy that I was able to wear it and it wasn't going to sit in a closet. It just reminded me of the beach – a beachy feel since we were going to be in Puerto Rico."
Catherine says her favorite moment during the wedding was seeing her son "marry the love of his life" – and getting the chance to dance with him at the reception.
"It was very important to me. It was this country song and it just kept playing on and on," Catherine says. "And all I did was cry."
The couple, who have been together for six years, left for Puerto Rico a few days after their hospital wedding to wed for the second time in Puerto Rico on April 23.
"I told everybody, 'We're a family, you have to go down there and support them no matter what's going on here,' " Catherine tells PEOPLE of encouraging the rest of her family to attend the wedding in Puerto Rico. "You have to make sure you go down there and be there with your brother and make sure everything goes a-okay.' "
Catherine remains at Stony Brook, where she has just started her second round of chemotherapy. She plans to have a bone marrow transplant when she is in remission.
"I love my family," Catherine shares. "That's what keeps me going. It doesn't even look like a hospital room – I just have all these pictures of my family and my friends. I have a wonderful support system."