Hello Kim, with my Crassula ovata, the coldest I have exposed it is in the 20F range. It is dicey, since in my area our winter cold comes with rains. Then it still gradually warms up to the mid 50F during daytime in winter.
This is how my Crassula ovata looked like in Feb 2012 when we had that episode of winter rains which came intermittently, and dropping temps in the 20F range at dawn. I think the other factor that saved this plant, it was positioned close to our house and at that time all the city trees are dormant, so there is more light coming in to our patio. Duration of that 20F range comes around at dawn for about 1 to 2 hours. It is really enough to do significant damage as well to my other succulents. If temps just linger in the 30F range and not much rain, then they survive much better. It is after all an active winter growing succulent too.
So depending on how your winter comes around there. If you get hail, snow, rains, that will further affect the survival chances of your plant. I would certainly feel dismayed if your plant suffers too much. So in your area, if that plant is mine, I would bring it indoors. Cool and dry but with lots of sun access, preferably south facing window is the best location for it and do not water often since it is indoors and not consuming a lot. Once your overnight conditions improve at least in the 40F to 50F range then you can safely bring it out again in mid Spring so it can resume outdoor growing once more.
