"She was one of the strongest women I have ever known — fighting her cancer like friggin' Rocky, enduring chemo, immunotherapy, a tracheotomy, feeding tubes for months on end, and experimental cancer treatment trials," Katy captioned the post, which featured a number of photos of the two as well as a video clip.
"I watched her go through many stages for over a year, but a few things remained constant: her sarcastic/wicked sense of humor, her positive outlook, and the incredible love she had for her family," she continued.
"She was like a big sister to me, showing me the ropes and always having my back. She never became a yes-person and was quick to check me when I needed checking — that was family," Perry added. "I have procrastinated posting this because it makes it feel a little too final, but I don't believe people ever really die — she just had to leave that body behind. Out of the body, and full of spirit now. Sadly, she also left behind two amazing young girls, and an incredible husband who was the definition of ROCK through this whole process."
"She may be gone from this place, but she will never be forgotten," the singer also said. "Rest in power, my angel, and don't worry, we got Chapman and the girls. #RIPGeli."