Unless he has a gun, you go to prison, or you spend every penny you have staying out, and end up penniless, homeless, unemployable, and possibly in prison anyway.
No...just...no...
The use of lethal force must be necessary, and proportional. And the standard of judgement is "reasonable man"...who knew only what the user of force knew or had reason to believe.
So, necessity comes from the ability, opportunity, and intent of the person doing the threatening. A lethal threat only exists if that person is capable of killing or doing severe bodily harm (ability), that person is close enough to do so (in your house certainly qualifies), and they have the intent to do so....and if all three of those elements are present, then a lethal response (which is proportional) is justifiable.
Now, if the defender reasonably believes those three elements are present, the shooting (proportional response in defense) is justified...even if we later discover that their perception was wrong by discovery of facts that were not evident to the defender.
So, a much larger adversary, or one armed with a knife, or a bat, or a golf club, or more than one adversary, would present a lethal threat if they had combined that ability with the intent (breaking into your house) and the opportunity (they were in your house).
It's difficult to determine the intent of someone who breaks in when you're home. But short of a polite question and answer session, if the intruder(s) know you're home, then it's reasonable to assume that their target is you, not your new 4K TV and the the wife's jewelry. Making certain that they know you're home is prudent (racking shotgun slide, shouting the command to get out, etc. are all reasonable techniques to determine intent) but only if you've got the time to do so.
So, it's pretty easy to see that the intruder without a gun, who breaks into a house, say, the house occupied only by a 130# woman, would present a lethal threat to her and her shooting him would be considered self defense under the law.