you're OK!
Dunsforo,let me add my .02 to this very worthy discussion.I tend to agree with the double charge theory.
I have been loading for over 20 years and I have loaded lots.Never had the catstrophic incident you describe,though I know they happen.
Contrary to what 1 contributor said,you would likely have been responsible for injury to another.Think about it:had your gun gone boom and hurt the guy in the next port,who would be responsible?
I have little hesitation in using any old brass that will go through the die after I clean and visually inspect them.Literally.I have 45 ACP brass that I have fired so many times the case rim won't go into the shell holder,it's so battered.That can be fixed if you want to buy the machine! I toss them at that point.
The brass is unlikely to be at fault.I have had numerous case ruptures in revolvers and rifles with no bad consequence.Semi auto actions open on their own and spread their good news easily,ie,what the chamber once contained.
Did you examine the gun for an overly stoned sear?It is possible that you had a slam fire mishap,which can be caused by a gun defect..not sure,but I think weak springs can also contribute to that.
To conclude,
The problem is your responsibility,but not necessarily some fatal flaw that should cause you to stop reloading,or from sharing your guns and handloads.It does show the importance of attentiveness...I ride a bike and have done for over 30 years ,and we say(not necessarily true,but a good philosophical outlook) that of bikers,there are those who have crashed,and those who will.
Don't beat yourself up.Thanks for the instruction.