"I shared the battle with her, and to just know that it was over and there was nothing more we could do was really hard to accept," Elizabeth Laudadio tells PEOPLE

By Gabrielle Olya
Updated July 17, 2015 09:00 AM
Credit: Courtesy Laudadio Family

Even though her sister Kathryn had struggled with anorexia and bipolar disorder for nearly a decade, nothing could have prepared Elizabeth Laudadio for actually losing her to the disease.

“She was always planning for the future to get herself to where she wanted to be, so even though she was so sick, when she did pass away, it was still a huge shock,” Elizabeth, 21, tells PEOPLE. “I had spent almost 10 years of my life watching her struggle, and always being hopeful that she would come out on the other side.”

“In that way, I shared the battle with her, and my family shared it with her,” she continues. “To just know that it was over and there was nothing more we could do was really hard to accept.”

What made it even harder was how these difficult conditions contrasted with the naturally warm and outgoing person Kathryn was before dying at age 22.

“There was a huge dichotomy between her radiant personality and the really horrific ugly disease that unfortunately took her life,” says the Connecticut resident. “Many of the friends that she made had no idea what she was dealing with. She was the most captivating person that I’ve ever met. She could make friends with anyone, and let any person feel special.”

While Kathryn spent many years of her life in and out of treatment – including four visits to inpatient treatment centers – one way she coped with her disease was through her passion for fashion.

“She really liked using it as a way to express herself,” says Elizabeth. “In particular, she was drawn to shoes, and the reason for that was that a shoe size is something that you’re born with, and it’s not something that you can change. She enjoyed being able to accessorize a part of her body that had nothing to do with her weight, and had nothing to do with her eating disorder.”

Kathryn amassed an impressive collection of 200 designer shoes, which her family is auctioning off beginning July 27 through the charitable re-commerce site Fashion Project to benefit Project HEAL, which funds inpatient, residential and outpatient treatment for eating disorder sufferers who want to recover, but don’t have the finances for programs.

“I think that Kathryn would be very proud that her life, though it ended tragically, can hopefully help people into recovery,” says Elizabeth. “The money that we raise from this can definitely help.”