I'm very sorry. Nothing prepares you for it or softens the blow. Your experience played out much like ours, we had no idea it was going to happen until we were in the moment. I've come to believe dogs are higher beings, at the very least they're more pure than us. I believe they know when it's their time and they welcome the relief from their suffering. This, in no way, makes it any easier. Two days before Amstel left us or son was visiting and Amstel walked into the middle of the living room, and just stared at my wife and son until they agreed to go on a walk with us. He had never done this before. During that walk he was like a puppy, he barked and wanted to run like he did when he was young (only it was for about 5 feet instead of 5 blocks). Amstel just wanted one last walk with "his pack". The only thing that I've found to stop the hurting is to remember the good times, to imagine his spirit is still around, as long as I do this the void of him not being here is tolerable. Again, I'm sorry. I hope reading this didn't make you feel worse. They are such special souls.