Piper's mother, Diane Piper, quit her job to focus on her daughter's care.
"I thought, 'Well, I'll have to give up work. Kate won't want to go anywhere. She won't want to be seen by anybody. She'll become a recluse. I will give up my life; I will stay at home with her,' And that was the future. An empty future," she said.
But even after a marathon of reconstructive surgeries and Piper settled in at home, the fear did not wear off. She was terrified of anyone approaching the house. Even the doorbell was immobilizing.
"It was like having a child again, instead of having a woman," her father said. "If somebody dropped a tray, she would nearly come off the bed. ...She was so frightened of men, generally, and just anything that was scary. And she had terrible days of, you know, hallucinations."
Eighteen months after the incident, the former self-described "party girl" decided to throw a party for those who were a part of her terrible but triumphant journey.
"I'd accepted that this was me. This was my new, beautiful face," she said. "I'd had a lot of help from the people that really mattered. I wanted to thank them in a way that I could ... and I knew it would mean a lot to those people to see me enjoying myself and out. I think that was a reward to them and to me as well."
ABC News' Justin Sturken, Jessica Horning and Lauren Sher contributed to this report.