Don't give up shooting. You made a mistake. Because you followed the 4 rules, no one was hurt. (#3- Be sure of your target and beyond.) I had an ND this last summer, and because I followed the 4 rules, no one was hurt. (#2-Never point the gun at anything you do not wish to destroy.) I had an ND taking the (very unergonomic
) safety off on a Mosin Nagant. It was pointed downrange, the only damage was to my pride.
We have about the same amount of experience, and are about the same age. You were given a reminder about the importance of the 4 rules, and you have taken them to heart to the point of doubting your abilities. Don't. If anything this incident will make you a 'safety monger', as mine did me, and it has served me well. My nephew did the same thing you did, except, there were no dividers, it was outdoors. Yes, he was done shooting for the day. Yes, I reiterated the 4 rules to him, and had him recite them back to me, with a promise from his father that he will continue to burn them into his memory. No, I did not ban him from shooting with me. I know he will be extra vigilant henceforth. You will be, too.
I wouldn't blame you if you probably go to another range for a while
, but please don't give up shooting, or instructing new shooters. You're much too valuable to us, the shooting community, to just hang up your hat.