Important considerations to have are where you will store the weapon. I know you have some children, so having it easy access is a no go on all fronts. No matter how responsible they may be, a friend of theirs may not be.
So you will need either a gun safe and or a trigger lock. Gun safes can come in small sizes, with a spot for you to quick punch a code in, or to unlock with a key. Accessibility is less of an issue with this, and you can keep it close by.
Some trigger locks are use a key, some combo, and there are a few that use a resistive band (think strong elastic) that a child could not release unless they ate a lot of Wheaties.
There are of course, other options such as a home security system, a loyal animal. Pepper Spray, hand held stunners ( like a tazer, but does not shoot out a needle, point of contact only), and the old trusty baseball bat.
When you purchase a firearm, you enter a whole new world of laws, rules and regulations that you need to be fully aware of before you decide to buy. You need to know if firearms are legal to possess and carry in your area (in Illinois, weapons laws are crazy, you have to have a special ID just to buy ammo). Will you need a permit? Will that permit require you to take classes?
If you have never fired a weapon, then you need to get some trigger time in, and probably take a safety class or many. It's not a big deal to us as trigger pullers now, but at one time none of us had any idea about firearms, and we spent a lot of time learning before they ever let us touch one.
Now, onto another issue, you do not need a pistol to overcome the sense of being a "sheep." That mentality comes from self confidence, and a bit of knowledge and training. I think your first step should be to consider a self defense class and exercise program, simply because you could run into a situation where you need to defend yourself and shooting the person is either not possible or inadvisable. Also, making the decision to not be a victim, is often the most important step.