I just put my dog outside to die and don’t know what else to do

I have a 15 year old dog, mix of husky and German shepherd. He’s had a great life so far but he’s declining. Since the summer he started having seizures, about 1-2 a day. He almost always falls over and pisses himself. This was hard to watch but my sympathy for him overrode the disgust. The vet said his heart was bad and his brains were basically rotting. We live in a poor country so not much vet care options. I just took him outside a few hours ago and left him in the garden. There was a huge puddle of water and I could see him shivering. I just came back inside and am going to take care of my other younger dogs. He’s been my loyal companion for years. I always felt bad leaving him alone or when he had to sleep outside of my room. God I hope he can die soon. I don’t have the balls to kill him and I don’t think any vet would put him to sleep.