Help Dennis Give Leo a Peaceful Farewell

My name is Dennis. It's been 12 years since I met one of my closest friends. He's been by my side through some of the worst times of my life and some of the best. His name is Leo. He's a 80 pound boxer Pitt mix. And recently he's become extremely sick. Too sick for me to do anything to help him. On the night of May 13th he was struck with a series of powerful seizures that have left him practically crippled. It's gotten so bad in such a short time that he can no longer move or function. I don't want to see him continue to suffer so I've made the tough decision that it's time to let him go. I don't have the money to currently, but I don't think he'll last the weekend at the rate things are going. If there's anything anyone can do to help me I would greatly appreciate it. It's almost 700 dollars for my vet to put him to sleep, cremate him, and return his ashes to me. I would really like to keep apart of him. Thank you all in advance.