"She was shot dead," Marquez-McCool's sister-in-law told the New York Daily News. "That's how much she loved her kids. If it weren't for her, he'd of been shot."
The day after the massacre, Henderson, 21, posted a short message on Facebook.
"I was just with my mom 24 hours ago," he wrote. "This is so surreal. I love you, mom."
At Marquez-McCool's funeral at the First United Methodist Church of Orlando Monday, Henderson paid tribute to his mother.
"I just want to say my mom was the best mom out there. Everybody who knew my mom knew she was the mom everybody wanted," he said. "I never thought that her life would be ended right in front of my eyes. My mother accepted everyone with open arms. She loved everybody equally, no matter what. I haven't stopped crying since."
While speaking, Henderson was almost unable to stand. His brothers rushed to the pulpit to help him stand while he pushed past tears to continue speaking.
"I didn't want to speak because I knew this was going to happen, but I knew I would have regretted it if I never spoke," he said.
Henderson said he and his mother used to wrestle and "play fight."
"I obviously lost. She’s a linebacker," he joked.
Robert Pressley, Jr., another one of Marquez-McCool's sons, sang a tribute to his mother, occasionally pausing during the song and holding down his head as he fought to sing through tears.
Her brother, Michael Santos, struggled to speak at the funeral.
"I have nothing to say to you because my heart is on fire," he said. "I have no words."
Marquez-McCool had moved to Orlando to live closer to some of her children. One of her children talked about how she always wanted to see her family together in one place.
Farrell Marshall, Jr., one of Marquez-McCool's sons, told people at the funeral to never take anything for granted because you never know when someone you love is going to be taken away from you. He last saw her before she went to the club.
"I wish I could give her a hug and tell her I love her," Marshall said. "I went from seeing my mother's smile to seeing her in a coffin. I'll never see her smile again."
At the end of Marquez-McCool's funeral, the family released dozens of white balloons outside in her honor.
"A lot of people called my mom 'mom,'" Pressley said in a video on his Facebook account. "My and my brothers and sisters, we're doing what we have to do, but my mom wouldn't want us to be sad. She'd want us to celebrate. She always told me that when she passed away she didn't want us to be sad. She wanted us to party and celebrate her life because my mom never had any regrets."
He continued: "She passed away doing what she loved, supporting her kids and having fun with her kids. She wasn't supposed to make it -- she had cancer. She was a fighter. My mom was a fighter. They told her she wasn't supposed to live eight years ago."
Marquez-McCool, 49, was a New York native. She liked to salsa dance and posted a video on her Facebook page of her dancing with a friend inside Pulse just hours before Mateen stormed the nightclub. She was a two-time cancer survivor.