When I lost one of my rescue pigs, who had a lot of medical issues in her life, I cried and cried and cried for ages! I find that I cry more when animals die than when people do. I don't think an animal's death is more significant, I just feel that we are so responsible for them and we put our hearts and souls into giving them the best we can that all that effort we put in has to come out somewhere when they die. I guess, on a lesser scale of course, it's like having kids which is why it's so harsh that they only live 5 yrs on average :'(.
I know just what you are going through and I hope you're able to think of all the amazing times you had with your pig and how lucky he was to have an owner who cared as much about him as you do. ((((((HUGS))))))
Gina x