I am very sorry about your loss. We all understand that you are angry not only at your dog but at yourself, but please try not to be too hard on either one of you. The dog really does not know that it was wrong and you did not mean to let the door open. It was a mistake in judgement. It happens to us all. When I was young and had rabbits, I thought my cat would like to see the baby rabbits so I lifted her to the open cage and she grabbed one. It was a terrible thing, and I learned a hard but valuable lesson.