No shame in what you did uncontrollablereaction, walking out from a fight is probably the best part. I have been a mad aggressive kinda person in my youth and fist fights are just a 5 minute adrenaline rush, it feels stupid afterwards, no matter what the outcome.
If you feel too strongly about it and it is a izzat ka mamla then may be it will be good for you to throw in a few punches next time you are in a situation like above. First of all no body ever dies in a street fist fight, not even broken bones, only a few cuts and bruises. Broken bones normally come later, if you have messed with the wrong crowd who know you, because they will come after you 
Aggression is the key to the fight, be the first to throw the punch, dont think, just go crazy. Remember not all from the opposition will fight, half of them will try to mediate and just push you back, never hit the mediator, just focus on the one that actually fought you or the one you dragged into a fist fight.
Also remember if the other side starts of talking then they are not into fighting either so dont hold back with your verbal aggression (still keep it limited to the person and dont get in punjabi curses and never ever abuse the other persons family, keep it respectable), that will help you calm down too. People who fight normally start with in 30 seconds of the argument. You dont have to start a fist fight if the opposition is not the one to fight.
Last year I was driving in Islamabad and these 2 cars were driving slowly side by side the passengers talking to each other, I honked for them to give me way but the didnt. Both cars were full and when one of them finally let me pass I swerved and gave them a side. Both cars started chasing me and at the traffic light about 150 meters from where I passed them one car blocked me from the front and one from the back. I had 2 friends with me. I just grabbed my steering lock came out of the car and ran towards the one at the front screaming like mad aaaaaaa, swinging the steering lock in the air. Two guys who were trying to come out from the front car just went back in and the driver who thought the maniac is going to hit their car broke the red light and sped away. I turned back and 3 guys from the back car were out and were very agreeable after seeing how I was reacting, “Aap pagal hain jo side maar rahay thay?” Anyway it probably took 2 minutes when they walked back to their car saying sorry for not giving way at first. My friends didnt even step outside. Confidence is the key to avoid the fight and aggresion to win it.
If you are in a fight and the opposition pins you down to the ground and are too strong for you and cannot run away, just roll into a foetal position and cover your head and face. In such a situation, the least you resist the the sooner they will let you go.
Also never get into a fight when you have family with you, particularly females. Normally people in Pakistan will not even get aggressive with you if they see you with family, it is the un written rule to give family some respect.
I havent had a fist fight in a looooooong time and can tell you that if they were to happen now, I would have walked away 95% of the times.
