oH jeeze, that is NOT easy. Your annecdote from Band camp rang true; I have been involved with string instruments and music camp was a wierd mix of fun, improving one's skills, yet also VERY heirarchical, product vers. process oriented, and very stressy. I could understand both your anger and her defens9iveness under those circumstances, and the best I can say is that she and you need to give each other a chance to grow beyond that time. It is hardly a "normal" situation.
I might make a suggestion and I hope you'll bear with me. Analytical as you are, it might be hard to drop the breakup, but it might be worth doing it if she doens't see how taking it apart will help. You might have more to gain just being her friend for the time being. You might discover some aspects of yourself that might surprise you, if you can bear to get out a little more. Huggs, I know there aren't easy answers, and I think the idea of hanging out is good, if you can just keep your expectations down.