Have no doubt about it, you did a very brave thing and you most likely saved an innocent person's life. Not to second guess your actions, but only to say what I would have done differently, I would have grabbed this:Jesus told us in the Gospel; no greater gift a man has than to lay down his life for another.
instead of a handgun. I carry a concealed handgun daily because it's what I can carry without making everyone around me nervous but still have some degree of self-protection. But, if I was going into what I knew was an armed situation, and had something else at my disposal, I would want something which gave me the advantage over a BG armed with a handgun.
Thank you for being willing to risk your life to protect another and don't lose any more sleep over it. You did just fine.