"When my two youngest children, Bella and Anwar, were diagnosed with chronic Lyme disease in early 2012, watching my babies struggle in silence in order to support me in my journey, struck the deepest core of hopelessness inside of me," the Real Housewives of Beverly Hills star said Thursday night of daughter Bella Hadid, 18, and Anwar Hadid, 16, at the Global Lyme Alliance inaugural gala.
Foster, 51, who was diagnosed with Lyme disease in 2012, was surrounded by family and friends – including Bella, Anwar, daughter Gigi, husband David Foster, her mother and Gigi's boyfriend Joe Jonas – when she accepted the "Power of One" award in New York.
And her eldest daughter even had the honor of introducing her mother.
"I remember when she was going into the first season of filming, she said to me, 'I don't know why this show was brought to my life, but for some reason, I think it will lead to something bigger,'" Gigi, 20, said onstage. "She realized that she could use this platform of this world-famous television show to spread awareness. She was honest, unapologetic, and raw in how she portrayed Lyme disease on social media and on the show from the second she announced to the world she had been diagnosed."
Foster dedicated her honors to her children.
"This award is for Anwar and Bella. This is my token and my promise to you that I will not allow you to live a life of pain and suffering. I will walk to the end of the earth to find a cure so that you can live a healthy life that you deserve," she said in an impassioned speech. "No child should suffer the way that you do ... I thank you both for your extraordinary selflessness during this journey. Your unwavering love and compassion has kept me alive and fighting through the darkest days of my life."
And the mother-of-three explained how the debilitating illness sometimes impeded on her parenting.
"I am so sorry for all the important things I have missed in your life these past four years," said Foster, who at one point lost the ability to read and write because of the ailment. "I used to be a pretty cool, smart, multi-tasking, kickass mom. But all three of you, all three of my children really got short-changed with a dumb blonde in the white robe, that mostly lives her life in bed," she added.
Despite the bad times, Foster said it has brought their family together in more ways than one: "I did turn into a professional social media stalker, though—liking every Twitter and Instagram you have ever posted, just to let you know that I was watching you from afar and right by your side in spirit at all times."
In addition to her family, three of Foster's RHOBH pals – Kyle Richards, Erika Jayne and Kathryn Edwards – flew in to support her on the big night.
"There's so much negativity that comes with doing a reality show, but it's time like this where you think: Okay, this is actually something positive that we can do and bring awareness to and just be a moral support for her," Richards tells PEOPLE. "So that's why we're here."