I never got to say good-bye?

I am 14 and had a shi-poo dog. I put my dog on a leach outside by my deck. Then i took a quick neck. When i went to go check on my dog, he was hanging of the deck by his leach, dead. His eyes were blood red. I keep seeing the picture in my head every time i go to bed. I do not want to eat or do anything. i will never be able to hear his bark or spank him when he pees in the house. i will never be able to walk him around the neighborhood or hold him tightly. I miss my dog