heyyyy ya, i'm sooooo sorry to hear you got such a nasty injury, BELIEVE me i can sympathise with not being able to exercise and henceforth getting cranky :P
i have stress fractures in my spine, (thank you, gymnastics) and a list as long as my arm of other injuries that cause me a certain amount of grief on a daily basis... the only thing i can tell you is this:
your body will probably NEVER go back to being the way it was (pre injury) but if you take care of yourself now and really work at having a positive attitude (I KNOW harder than it sounds ;)) but attitude will heal your body amazingly
and i really dont see any reason why you cannot go back to teaching, just keep your strength and stuff up now as best as you can, take different things (tai chi, aqua aerobics - probably sounds boring i know) but these things will hopefully a) stop you going out of your mind till you can get back into it and b) help you retain some of your strength and muscle tone in other parts of your body...
there always is the possibility that you will maybe have to teach something less high impact... (balance etc) but try not to focus on that... but also it is my strong belief that your body gets injuries for a reason...
i was an gymnast training at one of australia's elite institutions till about 3 months ago, and i loved gymnastics more than i loved my own life - and it almost killed me... an outrageous pain in my elbow (which now needs surgery) finally got me, and the physio took one look at me and nearly keeled over... i had (by then): stress fractures in my spine, needed surgery on BOTH my elbows, dequervanes tendonitis in my left wrist, stress fractures in both shins, my pelvis was displaced and i just felt *** all the time....
and to this day i love gymnastics more than anything, but in my interim i was forced to quit gym and found body balance (which i HATED at first) lol but learned (over the period of MONTHS) to love... you will find something else if you cannot go back to instructing what you previously were... and it was my time to quit gymnastics, my mind just wouldn't let me ever admit it, so my body had to step in and tell me...
i'm not sayint this is what's happened to you... but just something to consider...
"This is my body and I can do whatever I want to it. I can push it, study it, tweak it, listen to it. Everybody wants to know what I'm on... What am I on!?! I'm on my bike, busting my ass 6 hours a day. What are you on???"