Steve - I'm so sorry to hear of your tragedy! I am also sad to hear that you tore down your coop. The only thing worse than having your chickens killed is not having any chickens. Here is the speech I gave my kids when I brought home the first birds.
"Chickens are prey. Everything eats chickens. The neighbors dogs will come to try to eat them, our OWN dogs will try to eat them. Opossums eat chickens, raccoons eat chickens, hawks eat chickens, rats eat chickens. Heck, WE eat chickens! Chickens are food. Something will eventually eat them. Do you understand?"
With that said, we first acquired six chicks and still have five of them over a year later. One was lost to some mysterious ailment. We have, however, lost many guineas and six of the next twelve chickens we bought. By the way, the boys took the losses much better than I did! Losing birds is part of keeping birds, just as falling off a horse is part of riding. Please don't give up. Get back on. Okay, the old coop is gone, what a wonderful opportunity to build a bigger, better, more secure coop to house the new chicks that you will get in the spring? Your wife and daughter will be stronger for the experience if they see that life goes on and that they can get through and over it. Don't let it end in defeat! Here are some suggestions on a better coop, you can find mmmmmany more here and maybe doing the research on coop security would make a great family project.
1. Figure out how many chickens you want to keep
2. Plan for your coop to hold at least twice that number
3. Build enough room that they don't have to be let out to free range (even if you plan to let them)
4. Make it as secure as possible. It will cost more at the onset but will be worth it later in peace of mind and in reducing losses.
I know that my coop (pics on my page) and run are not predator proof, but I don't worry at night when they are locked up, about the "big" ones. No dog, coon, possum, owl, bobcat, coyote, etc. can get them. I still haven't made it weasel/mink proof or snake proof as those can get into a much smaller hole. I have 4x4's set in the ground for supports, 2x4 welded wire covers the entire outside and is buried down 6" then turns out 12". The top is covered with metal roofing. Once they are locked in at night, I sleep soundly. All of my losses have happened during the day when I let them out and as heart breaking as is is to lose one, I still let them out to be chickens. That is the choice I have made. If you simply can't take the chance, then leave them up unless you are out with them (although there is still no guarantee, as some have reported having birds snatched right in front of them.)
I know you are mad (at the cat) and heartbroken for your wife and daughter, but it really can be turned into a learning and growing and strengthening experience if you just don't give up! Go ahead, put your foot in that stirrup and climb back on... you're not beaten until you give up and quit.........
*NOTE* The above message was meant to inspire, how'd I do?