I shouted and I feel bad

We don't believe in laying our hands on Ryan or any of our children now to discipline them. We believe reasoning with them would be a better option. However, how do you reason with a growing super energized child can sometimes be a real challenge and a great test of our patience, mine in particular. Ryan can be a real angel on his good days but he can be the most irritating 'torture from hell' if he chooses to throw his tantrums and be real nasty. So far, we thank God that he is still fearful of the 'naughty corner' punishment and that has helped to keep him at check every once in awhile. Getting him to school early in the morning has always been a challenge and unpredictive. He can be one super angel, eagerly waking up and getting ready to school with hie best smile or he can turned into one of those nasty little demon that you would have to literary drag into the car. Yesterday morning was one such morning. We managed to wake him up early and got him dressed. He was cheerful for awhile and then out of the blue, his nasty side took over. He wanted to watch tv and not want to go school. We tried reasoning with him and got him into the car but he was still whining and crying away, repeating and repeating that he wanted his tv. I tried hard to explain that it is school time and he promised him that he can have his tv when he comes back and does that work? Oh no. He whined and cried even louder. My patience was running thin. I normally don't do this but I can stand him no more! I raised the top of my voice (and I can be very very loud)and I shouted at him to stop and to behave. I think he was shock. I was. He stopped immediately. Not a sound from him till he was drop at his school. As I drove off, I felt very bad. I don't know why? I felt guilty for not having more patience. I felt bad that he is just barely 4 years old and he did what every child would do. I felt uneasy and have that greatest fear that somehow that shout would leave a lasting damaging effect on him.. Did I do the right thing? What could I do differently? I really don't know. I am just trying to be the daddy that I could be within my human weakness and limitations ....