I dislocated my ankle and tore 4 of its ligaments a few years back, so it's a bit different to having a fracture in there as well - that would be the main worry with any exercise, regardless if it's a complete fracture or hairline etc. You should be alright with most upper body exercises - just be sure of your balance as you could use the bad foot in a reflex if you aren't properly careful (as I did - it hurts!).
Also if you're sitting around a lot it would be worth having a look at basic range-of-motion exercises for your back and upper body as well as knees/hips if you can. And with the upper body work you can use much lighter weights and use it as more of a cardio exercise than for muscle.
Try and work your other leg a bit, though crutches will also give you a bit of a work out and the sole use of one leg will help it, the leg that won't be being used will be a fair bit skinnier in 2 months time!
I think just try out your exercises in a couple of weeks and find the ones you're most comfortable with and go from there. Sounds like you may get a full cast which is more intrusive I guess, I had a back slab of plaster down my calf and under my foot so I could shower without it when it eventually didn't hurt to try and remove - this also allowed me to get into a pool after about 6 weeks - lots of exercises can be done there particularly holding a board with your thighs to prevent any other leg movement.