Home invasion- Protecting oneself?

Here is a scenario- Since home invasions seem to be the new "thing" nowadays, say I was alone at home during the night or day and I'm upstairs and I hear someone break in and start running up the stairs and come into my room(and I see no visible weapon), so I grab a hidden gun in my room and shoot at him once before he has the chance to attack me, would I get arrested for protecting myself whether he died or not??? Lately, I've been thinking about keep something upstairs with me like a knife or something for protection cuz you never know and are hardly prepared.I dont own a gun.