Welcome to the world of concealed carry. I know you're not there yet, but you're starting the process. You're to be commended for taking seriously the personal safety of you and your loved ones. Try to get all the information you can. Yeah, the aspect of carrying a gun concealed is technically not that difficult, but it's a VERY serious responsibility not to be taken lightly.
I've been recommended to check out a Glock 17.
The 17 is a fine defensive handgun, but no one handgun suits everyone. As mentioned by others, I'd suggest you shoot a number of different guns so you can get a feel for what's best for you at this point in time. Full size guns are easier to learn to handle and shoot, but harder to carry concealed. Your first priority should be to learn to safely handle and shoot a handgun. A gun the size of the Glock 19 is a good compromise that's sized well to learn with yet can be carried concealed…….by some…… I say some because many find guns w/ a wide magazine (to roughly double mag capacity) less comfortable to cc due to the extra thickness. Understand that a "compact" version of gun only means the barrel and grip are slightly shorter than the full size version; the thickness is unchanged. And, remember that revolvers are always a good option. After you've handled/shot different guns, you'll figure out what you like and don't like.
Spend your time looking at guns from the major gun makers w/ a good record for reliability, i.e. S&W, Glock, Springfield Armory, Beretta, Sig, Ruger, etc. You don't have to spend many thousands of $$, but don't scrimp, either.
I don't know anything about firearms. Where do I start? Where in BR should I go about shopping for a handgun.
Get some formal training. Not living near BR, I don't know who to suggest.
Used guns are fine, but you may want to start w/ a new one until you know more about handguns.