Parents that let their kids run wild in stores?

OK, I was recently shopping with a friend and we were trying to get everything we needed because we did not have time to go to any other stores or make a second trip...and we were so overwhelmed by the loud mother and her even louder child...I would say he was about 6. It seemed the more we try to get away from them the closer and louder they were, so bad that we could not even concentrate on what we were there for...the boy was running up and down the isles knocking things over,yelling to his mother who was a few isles away,etc,etc...OK..when we went to the check out area they were there...and only ONE check out open and that meant standing right behind them...then a second check out opened and I said to my friend "thank God because I have had enough of this kid" (I knew the Mother heard me but I was careful not to let the kid hear me)...WELL she starts yelling "I heard that" repeatedly and had her what looked like grandmother take the boy out to the car. She then starts screaming at me after she got checked out that "I am sure your kids did the same thing when they were little" "he is just a child", etc,etc....my come back was "it's not a playground". She waited for us to exit the store and then shouted obscenities and said "I should ram this cart right into your car b****". Was I totally wrong in my actions?