I dont think you should get down on yourself. You did the right thing by bringing him home. If he would have stayed at school he proble would of had a bad day.
I had a simular problem last year with my 6 yr old son. He through a fit all the way to school screaming at me telling me that i was going to make him dume if i did not let him go but i knew that if i let him go then it would have been a really bad day and he would have been in the office half the day.
Letting him know next time that he should be more concess not to leave his favorit shoe at someone else house so he dose not get mad the next morning when he wants to ware his shoes.
It is hard with them at that age for some reason they just dont want to lissen to what you have to say. And if they dont like it its our falt.
but you did the right thing just hang in there i know i am and i am sure someday the will understand ware we are comming from.
I am a mom of 2 kids one 7 and the other 1.