In the state of VA what is reasonable lethal force to protect against intruders?

My neighbors were brutally attacked during a home invasion a few nights ago, they have just apprehended all of the ailants, but threats were ped by them through family members just earlier the day of their arrest. Last night when the victim got home from being released from the hospital he was getting out of the car as a car slowly went down the road, a person outside the house named them out as the brothers of the attackers. The car turned around slowly went by us pulled over to the side of the street and started shooting a gun. As we tered the car sped off. My question is about self defense in my OWN home against a attacker. What measures can I use to protect my family? I really dont know much about handling a weapon but my husband loaded our handgun for me and told me not to hesitate to use it. Is there holes in the self defense law? I want to protect my family here but at the same time be doing it in a legal manner that wouldn't cost me any problems.