I know boys and girls are very different when it comes to TT but my son who had flat out refused to TT between 2-3y is a sheep. As soon as he saw other kids (ie his stepsister who is 3 months older than him) using the toilet, it was literally overnight for us at 3.3y. Before that he would cry and scream and have accidents, I thought it would never happen! But we went away for 5 days at New Years, we left him using nappies and came back with him fully TT (day and night). It was bizarre, but I think a lot had to do with trying to be like the others his age.
She probably sees her friends doing it at school so wants to be like them :-) see how you go for a week or two and if its still distressing her, wait a while before trying again, it's frustrating but you'll get there eventually