It took us quite a while to get over our girl when we went through something similar. My dh took it really badly, went into shock and had to take a week off work. I wasn't able to take time off and to be honest keeping busy helped, at least when I was away from the house.
We didn't get another dog straight away, but we did start making plans to as our other lad wasn't happy as an only dog. We started researching breeds and breeders and went on a waiting list for a puppy (it was a breed that meant we ended up waiting a year for a suitable pup to become available). That gave us time to grieve and come to terms with opening our hearts to another pup.
Please don't feel you couldn't look after another. It was a freak accident - and I have no doubt you would put everything possible in place to make sure it couldn't happen again.
Our girl was being looked after by someone else when it happened, but I don't blame them. They took their eyes off her for a second while she was in what they believed was their secure back garden - she had sussed an escape route and was gone in the blink of an eye - no-one's fault, just a terrible set of circumstances coming together.
Please be kind to yourself and give yourself time and space to grieve and deal with the shock.
As for whether or not to get another dog, it's a totally personal decision, but bear in mind, whilst another dog won't be in any way a replacement, they may help to heal some of your family's heartache. Perhaps, when you're ready you could have a family meeting and a frank discussion as to how everyone feels about it?