I went through that about 4 months ago. It's definitely one of the worst feelings out there.
I was right in the middle of a very stressful and important engineering project for uni. I came home to visit my family for a weekend. She was fine when I got there, pretty happy and excited. Then at midnight, she started breathing funny and died. I hated that I got to watch her die. Even though she died quickly, watching her panic as she slowly struggled to breathe was the worst.
And then the next day, we had to move the body. I never realized how heavy she was, nor did I realize how stiff bodies get when they've freshly died.
I dunno. I think still to this day it has kind of fucked with me. I never had a great relationship with mortality before, and I sure as shit don't have a great relationship with it now either. I miss her calming presence. I miss walking into the house and smelling the unmistakable smell of dog. She was the coolest dog I've ever known.
It gets easier. Days will pass and it will hurt less and less. But yeah. It sucks, especially when you've got no one to talk about it with.