Our cat William ate a lily - help!

William is one of two fur babies we have. He is a 8 year old Tabby and is a member of our family. In preparation of our upcoming wedding in September, we purchased a bouquet of flowers from the grocery store to see how they looked in our DIY vases. That bouquet contained two lilies, which unknown to us, are poisonous to cats. The 25 pounder scaled the kitchen island and got to the poisonous flowers and nibbled on them. Five days later (yesterday), we noticed very bad symptoms and took him to the vet first thing today. From the poisonous lilies, he received notable damage to his kidneys and has been put under aggressive treatment. The treatment is $1000, which while paying for our wedding, is a lump sum of money we don't have right now. This is why we are setting up a gofundme for William and our small family. We appreciate any help you can give and thank you for caring.