In answer to the original question: yes, I felt bitterly like a failure when Cambridge rejected me. It wasn't bitterness directed at the university for their decision, but rather directed at myself when that letter reaffirmed the never-ending suspicions that I was no good. In effect, I was forced into applying by my school and became slightly deluded, and after that summer holiday doing nothing but preparation, I became the only Cambridge applicant to be rejected without even making the Winter Pool. It made me feel pathetic over how much hope I had put into Cambridge, alongside the insults from the students and teachers who had initially pressurised me into applying there, even though a large part of me had wanted to.
Looking back, I would never have managed at Cambridge. The college's decision was right: a deserving applicant got that place and will benefit well from the opportunity, unlike what I would have done. It's a shame that the application had to happen when I was in the mindset to epitomise it as true success, since achieving an Oxbridge place is only the very beginning of something very challenging. I will always remember my experiences of applying and wish that they had been successful - but those who did get places for my course were simply more suitable, and I am entirely content with that.