Can you legally "break into" your own house and shoot a dumbass like that at night? I know during the day it'd be hard road to go down but night time someone occupying your house it'd be protection of property wouldn't it?
No requirement to retreat on your own property. The very act of breaking into your occupied home uninvited is presumed to constitute just cause for the use of lethal force.
On the other hand, if you render the home invader harmless with less than lethal force, then killed him, you would probably be prosecuted.