Couldn't agree more with Christopher. IMHO, however, in addition to removing the lower branch, I would cut it back severely .. I would make it almost naked. Trust me, some good light and it will bounce back before you know it.

Looks like the signs of overwatering, which is easy with what appears to be peat based bagged soil. It also is very leggy due to lack of adequate light.

Joe

Cooler temps are not a problem, jade will be ok even little below 10C (all my succulents overwintered in abt. 8C, np). Just make sure it is not touching glass of the window in cold weather.
Are most of the red leaves small-young ones? They get red if getting lots of sun - it's not disease or anything bad
It would be best to take it out, get rid of soil completely; use chopstick or wooden skewer to loosen up the soil around the root ball. Rinse it off. Inspect the roots; if you see any mushy/black (rotted), cut them off. Also any dead roots. Set it on some newspaper for a day or two to dry.
When you take it out of pot, some branches may break. No problem, they could be potted and you get more plants.
Consider comments from previous posters -
Search this forum for lots of good info; here is just one of the threads, I am posting link to it since it has very good photos of roots being cleaned (also large jade):

re-potting jade-click here

These responses are dead on. To add to the trimming back, if you trim it back you might be surprised with how quickly it explodes with new leaves.

Looking at the first images a little closer, it looks like you have a plastic pot inside of the glazed porcelain pot. I had a lot of trouble growing any succulents indoors that are not in a terracotta pot. You can do it, but you have to be REALLY careful to not over-water, which is obviously incredibly hard inside since the sun can't help you dry out the soil.

Listen to these folks and your Jade buddy is going to be fine!

Thanks so much everyone for all the tips! I did go ahead and take 5 good cuttings from it today, I'm wondering if I should let the parent heal before I repot? The jade is in fact in a plastic "self watering" pot inside of a larger porcelain pot. When I first became concerned about over watering I took it out of the porcelain pot and checked the little drainage compartment which was bone dry, which doesn't necessarily mean I didn't over water but I'm not totally convinced as seems the symptoms of overwatering and under watering are the same. So frustrating! I'm thinking a terra cotta a size larger than the plastic pot it's in should be ok? I'm only nervous about over shocking the plant by taking the cuttings today and repotting too soon after. I considered repotting first but due to the size of the thing I figured it would be easier to repot after first trimming it back but maybe this was the wrong order to do things. One more odd question: I used root hormone on the cuttings I took today, and plan on giving them some time to callous before potting, but should I do anything with the parent plant where I took the cuttings from to help it heal as well?

Thanks again for all the help :)

Rina_ -yes, there are several new little leaves that are bright red but also a few larger ones. This was my fault because I got so used to admiring it from one angle that I forgot to turn it and all the leaves on one side turned red. Not damaged or anything, it doesn't really get hot enough or bright enough here in the winter/spring to do any real damage. :)

Don't worry about re-potting original plant if you pruned it. Can you post photo/close up where you took cutting? And maybe photo of whole plant after pruning.
You can re-pot it but make sure you have well draining mix ready. I don't think you need bigger pot but definitely not self-watering. Terracotta pot would be good - make sure it has drainage holes. Glazed pot doesn't 'breath'.
Rooting hormone is OK (I don't use it on jades at all). Let cutting callous and then pot up.
Red color isn't a problem as I mentioned before. I was just wondering if all leaves have red color.
Give plant as much light as possible.
Can you keep it outside once it gets warm enough? They grow very well that way...Rina

I did go ahead and re pot the parent, the root ball appeared quite healthy and fairly dry. No bad smell or discoloured roots so I think that's a good sign. I re potted with a succulent mix and added quite a bit of pearlite, I'm hoping this will be ok. There still seems to be a little bit of leaf drop but not nearly as much as there had been over the last couple of weeks. With that said, my Jade is as bare as it's ever been. Between the cuttings I've taken and the drop, it's looking pretty naked. I ended up taking 6 cuttings, even though I could have easily taken a dozen more. I was nervous that it would all be too much of a shock to the plant. Some of the cuttings I used root hormone, others I didn't. I've had success propagating from this Jade before without the use of any hormone, just thought I'd give it a try this time and see what happens. The cuttings appeared healthy, but I'm not really sure what I'm looking for in a healthy stem... After re potting the parent, I waited a day before giving a light watering but with distilled water this time as I've been noticing little crystals appearing on some of the leaves which I suspect could be minerals in the city water? I'm trying everything to bring this Jade back! :) I don't think I've made much difference to the overall look of the parent plant. 6 cuttings seemed to hardly made any difference at all. When the current cuts heal I plan on pruning back even more. I may end up with 1 parent Jade and 30 babies, but I don't think I could bring myself to throw them out.

As soon as we're back in the double digits I will be bringing it outside as much as I can. At the moment we are still at about minus 10 some days, but it will get warm eventually! In the summer we can get high humidity. I know Jade's do not like this, but would short periods of time outside be ok?