Thank you all for your kind words.
I just found out about my GF's dog dying on friday morning.
I spent time with my sister who I'm close with. I told her I was crying and that I feel devastated and at one point she said "Geez what's gona happen if someone close to you dies. It's just a dog" 
That pissed me off, but at the same time I guess it's hard to understand. That dog was like a baby to me. It feels like I've lost a child. I'm sure she's just trying to make me feel better and wants to put it in perspective, but that sort of s**t doesn't help.
Anyways once again don't let it happen to you. Just be wary that someone might try to steal your dog, it might try to run away, or get run over, or predators may get it, or it may get sick. All we can do is be prepared and try to prevent it as much as possible.
I'll try to just remember the good times we had. I'm sad, but already much better than when I first found out about her death.
Thanks everyone for the kind words, it makes me feel better that there are others out there that have real connections with their dogs. I'l get over this and life will go on. I just hope no one has any regrets like I do. Stay safe.
edit also my girlfriends parents, who were watching the dog, did not know that coyotes were actually walking that neighborhood. The last they had heard of a Coyote was a long time ago, and had no idea that it could scale a 6 ft wall. So we all need to be careful.