Both the slide lock AND the firing pin had to have malfunctioned simultaneously for the full auto accident to have happened, eh?
Did the slide lock really malfunction? Some are basically meant to close if you slam a magazine into the pistol hard enough - my Glocks do it all the time. Not necessarily a malfunction. of course it could have been a malfunction. As for the firing pin being in a bad position I guess that could have caused it, but what caused the firing pin to be stuck forward. Fouling and debris (such as brass shavings) are two of the likely suspect materials but you say the gun was very clean. Over oiling has been known to cause debris to get stuck in the firing pin channel/housing.
I don't know if high primers could have been the cause, but maybe. In that case there may have been nothing wrong with the pistol. The slide could have gone forward because of slamming a mag hard into the mag well, or because it was not latched fully and properly because of human error (just giving possibilities) then if each round had a very high primer, I suppose the face of the slide could have slammed into the high primer setting it off, this would have fired and cycled the pistol, loading the next round also with high primer, which also goes off in the same way, then likewise until all are fired. My guess is though that since you fired the same lot of ammo the week before with no problems, this is unlikely. Broken firing pin, and part protruding - Maybe.
There was one other possible malfunction by the way but, not the gun. That possible one was due to shooter error. How your hand wound up in front of the muzzle is a bit of a mystery. Maybe shoter error maybe due to the gun going beserk and catching you off guard. You have to figure that one out.
All in all, it was one heck of an experience. You can be happy the gun was basically pointed down range when it went off. I can understand how you geel unhappy tough, I would not be happy about a hole in my hand either; I guess just less unhappy that it did not do more harm to me or others. By the way, nightmares can be expected for up to many months after such an incident if it really traumatized you mentally. If they persist, it is normal but also a sign that maybe you should seek some therapy to help put it to an end. Selling some guns may help ease tensions at home but, in my opinion, will do little to ease the pain of this event.
Hopefully you will make a full recovery in the not too distant future. The wife and mother will get over it and realize you were not hurt more because you pretty much, if not altogether, did it safely. You will keep your guns and have lots of safe fun with them in the future. Safe shooting.
Best wishes for a full and speedy recovery,
Glenn B