As explained at GPDO:
"Defense of habitation; (here habitation means dwelling, motor vehicle, or place of business) A person is justified in the use of force which is intended or likely to cause death or great bodily harm only if:
A person is breaking\has broken into your home in a violent and tumultuous manner, and you think that the intruder is going to assault you or someone else living there.
A person who is not a member of the family or household and who unlawfully and forcibly enters the residence and you know it is an unlawful entry.
The person using such force reasonably believes that the entry is made or attempted for the purpose of committing a felony therein and that such force is necessary to prevent the commission of the felony."
Found here: http://www.georgiapacking.org/law.php