11 year old daughter wont speak to me?

My 11 year old daughter wont speak to me and hasnt for over a week - well hardly, she has also told the school councillor i am a terrible mum who does anything i can to destroy her life, i dont know what to do???? we went away for a day trip to a gymnastics comp in a town about 2 hours away from ours, i took her and her 3 friends, we got macdonalds for breakfast on the way out of town and they all got a soda and food, about 30mins into the trip we got gas and i told any of them if they need to use the loo to use it now as the rest of the trip is on the mainly motorway. 1 hour into the trip jess told me she needed to pee, i asked her how bad and she said she could hold on, we had about 35mins till a small town which i knew had a gas station. about 10 mins latter we hit bad roadworks and where still on the 3 lane motorway for about 15 mins - she told me she was now getting busting of course it was still a bit of a joke between her and her 2 friends they thought this was quite amusing, 10 mins latter she was desperate for the loo and started getting mad at me to stop she was holding her crotch and had gone very quiet, because of the road works we had about 15 mins to go. There was literally no where to stop, 10 mins latter we got to the small town it was just coming upto 8am and i raced into the gas station she was out the door before i stopped and cross legged hoping for the loo the door was locked and she wet her pants all over the step making a mive puddle on the concret she was in tears, i felt terrible. of course even though her friends promised they wouldnt tell but couldnt resist and the work sure spread round her whole school, she is furious with me i dont know what else i could have done. Please give me some advice