There is no easy way through this maze.
I faced a similar situation years ago in Florida on New Year's Eve. Somewhere around 1AM a clearly inebriated young man decided that he had to visit his ex no matter what. Unfortunately — or fortunately for her — he came to my house instead of her house. He went from knocking on the door and yelling obscenities, at which point I called 911, to attempting to kick down my door.
I was armed with an old Remington 11-48 12-gauge alternately loaded with #00 and slugs and an S&W M27 .357 with 125gr JHP screamers and had taken a position of cover diagonally across the room from the door. I kept the line open with 911, informed the police I had a gun and shouted the same to the miscreant on the porch. I shouted that if the door failed, I would shoot. My chow dogs, never the friendliest of animals, were in a frenzy and barricaded behind me; I had turned on the porch lights and shut off all the lights in the house, guaranteeing me a clear shot. The miscreant was shouting that he was not afraid of the dogs or the gun and that he was going to kill everyone in the house as soon as he kicked the door open. The police informed me to expect a 20 minute response time and to "do what you have to do to protect yourself and your family"...in short, I was in the strongest position possible for a homeowner both for the shooting and the subsequent legal issues.
However, the young guy was obviously falling down drunk, I could see both his hands and his belt and saw no weapons and it was New Year's Eve and I profoundly didn't want to kill that kid. I made a risky decision to give the shotgun to my girlfriend with the instructions that if I failed, shoot first, then turn the chows loose. I took the S&W revolver, inched toward the door (which was very close to splintering open) and from the best, most shielded position I unlocked and opened the door and stepped back into the shadows. All the miscreant could see was the muzzle of the revolver.
It stopped him cold. he raised his hands. Is that a gun, he asked me? I said yes. Am I going to die, he asked? I said that if he lowered his hands or made a fast move, I would shoot him. He started crying. I went through the usual drill to spread-eagle him on the ground facing away from me, feet crossed, hands palms up, yada yada, and got to hear his whole drunken life story, wrong house, sorry sorry...I waited 30 minutes for the cops, and when they didn't show I told him to get the hell out off my front porch, go home and sober up. The cops showed up about an hour later and said they'd have done the same thing.
Short story...I was well within my legal rights to shoot the kid if and when he succeeded in breeching the door, and I would not have hesitated to do so had he succeeded. But I decided to take the risk I took because I wasn't sure being drunk and stupid on New Year's Eve was grounds enough for me spending the rest of my life dealing with what my 12-gauge would deliver on command. I also never doubted my ability to make the shot if the miscreant made the wrong moves. It was a risk, but in my opinion an acceptable risk.
The reason I train is to allow me to go as far as possible, to know what risks I can take, before taking a human life!
One situation; one outcome. Food for thought.
Michael B