Wow! You were lucky in that you did not go into DKA! I got to 43 mmols and had all the symptoms you describe. My carers kept insisting that I had been drinking alcohol because they could smell it! (My poison at the time would have been vodka, which does not smell!). I was hallucinating in between vomitting into a bucket beside my bed. Was "watching" some really weird adverts on the telly - which was off! Or, trying to work out the lay out of a house with the "aid" of plans, which I could not, and kept getting lost!
I eventually was taken to the hospital and the carers insisted again that I had been drinking. While they were testing me for alcohol (which was zero, of course!) a man who was a Diabetologist walked into the ward, sniffed, pointed at me and said "That one has diabetes!" He is one of the few people who can smell the difference between ketones and booze! Apparently I was half an hour from dying!
Apparently I had a chest infection, and it does seem that I go crazily high if I have a chest infection but thankfully have never had to go to hospital since. I had been originally diagnosed as Type 2 but it turned out that I was Type 1. The doctors caring for me came to me the next day demanding to know why I had not taken my insulin. I was not on insulin at the time!
Stress can also cause really bad highs. Perhaps the stress of exams and revision might have had something to do with yours.]
I too pray that you never go that high again! Hope you have recovered!