So sorry to hear.
I got my dog on a whim. I figured if it didn't work out, I'd sell him or give him away. Well, I took him for his first shots and put him in his kennel when we got home. I'd check on him every now and then, and he just didn't look right - kind of listless. Well finally I decide, if the puppy is going to die in the night, it isn't going to die alone, so I put it in bed with me. I only half slept afraid I was going to roll on the thing, but did wake to find the thing licking me in the face.
So much for giving it away or selling it.
He's six year old now and my best bud. He's sleeping at my feet as I type this. I can only imagine the loss you feel, but I don't like to.