You can do just about anything :) Jades respond well to pruning and that plant needs I desperately. It would be better to prune it in Spring, but if you keep it active (in warmer temps and with lots of light and watered as needed), I think it could be done even now.

BTW, you didn't indicate your general location and growing zone...it would help if you add that info next to your name.

Here is example of heavily pruned jade in very late Dec. - all branches and leaves - and it's progress in following 6 mo (thicker trunk than plant you have):

Pardon me - I'm in central Pennsylvania. Wow, that was a pretty drastic pruning you did! I think I'll document my pruning too for the friend who gave the plant to me. Thanks for your direction. Your jade is going to be a beauty with that trunk!

I'd pruned it into a weeping bonsai in a tall bonsai pot, her's one of many images I got when googling "curly weeping jade bonsai"

https://goo.gl/images/JqJBWr

Sorry for the extra posts, my houzz is doing weird stuff today:-)

As Rina mentioned, if you can't give it strong light and warm temps all winter, then hold off the carnage until spring when you can have it outside.

Try to picture how you might wish it to eventually look. You can always start with a less drastic whack job if you are afraid of taking off too much. After all, you can always remove more later but can't exactly glue a branch back on (though there is grafting...) Plan on a full repot into better media and use that opportunity to perhaps position the trunk more upright -- unless you want to try for a leaning look. Personally, if it were my plant, I don't think I would cut it all back to the trunk. Instead, I possibly would keep the main trunk and cut back all the side branches to within 3" of the trunk. Hard to tell from the photos, but I think I'd remove that first low branch (the one just a couple inches above the soil line). If you choose to do that, make your cut leaving 1/2-1" from the trunk, The attached portion that remains should wither and fall off without damaging the trunk. Then I'd top the trunk after the 5th branch. Btw, jade cuttings usually root easily, so you could keep and pot up some of the removed branches if you wish.

Lisasfbay, I love, LOVE that photo! But I don't think this jade and that jade are the same. Mine has these sort of big ugly leaves. It's not the same as any of my other jades. BUT...thanks to your suggestion, I might go for that look anyway and just see what happens! I have a jade like the one in the photo. Maybe I'll give that a try with that one too. I can't stand throwing away any of the pruned pieces, so I have tons of little jades everywhere. I'm like Mother Hubbard with all these jades, so I need to do some experimenting to see if I can do something interesting.

Paul, I like your pruning suggestions. I am going to just take off a little for now and do the big prune in spring. I have three rooms torn up waiting to be painted and a barrel vault ceiling to gold leaf. I should ignore the plants and focus on winter projects. I think my husband would really appreciate if just one room weren't full of half dead plants and painting supplies.

Thanks for all the direction. I'll keep you posted!

Just to remind you that one of the aims/results of proper bonsai techniques is to reduce size of the leaves...So while I am not sure what is the plant in photo Lisa linked to, many bonsai "jades" shown in photos are actually Portulacaria afra - that is not a jade. Portulacaria afra has much smaller leaves to begin with, and slightly different growth habit. Look of trunk is slightly different too. But that doesn't mean it can't serve as inspiration ! :) You could have jade (Crassula ovata) growing in similar shape :) There is much more to bonsai than just pruning branches, but it is one of the important techniques.

What Paul suggested is probably best for now, especially if you don't have time. What I showed you is more of a partial answer to your question: ..."what's the most drastic measure I can take to shape it without killing the poor thing?"...

For now, just shorten all the branches and not prune any off, trying to get main trunk thicker/fatter. Good luck and keep us posted!