Fear is natural, but rehearsal and some routine "in case of" training goes a long way.
Like a fire drill at school, just think your plan through. For example, A small handheld air horn, like on boats, and at football games, sends out an audible blast that is LOUD. This generally will scare the crap out of any BG in the house, and wake everyone up. Including some neighbors.
A couple short bursts will wake everybody up. Than provide an explanation to your family members, that this is similar to a fire drill, and "x,y,z" will be your plan when you hear it.
A 911 call, a safe room, lock the doors, stay low, etc,...whatever your plan is, just have one your family understands ahead of time.
I told my wife to stay low and call 911, if I have to fire, I am aiming center mass or waist/chest high. She hits the deck, calls 911, and we hold up in the Master Bedroom.
When my son is here for the summer, and sleeps on the other side of the house, we have a verbal command, (small house), and he hits the deck, and calls 911. Cell phones are great that way.
Numerous options, as well as variables. 2 story houses, layout, etc,....play a role. Be cool, calm, and make it a routine that should also include, housefires, tornado's, or other emergencies that may effect your house.
Depending on the age of your children, this will be up to you to encompass the "Family Drill Hour" so everyone is prepared.
It's not impossible, and can be achieved. Good Luck, perhaps Rob, or Michael J, can chime in on SD Home Plans that involve children.