Well kitha1215, I need a few more details about what you observe as wrong, since the pic isn't very big. But off the bat I'd say, it looks like its in a pot that's too big for it. Have you potted up recently? Being in to large of a pot can be bad for your christmas cactus, esp. during the winter months, when a good watering in too large of a pot can be very detrimental--b/c too much wet soil next to the roots can cause rot as the roots are unable to absorb all the water surrounding them. It appears to be in a 6" pot. I would down grade to a 4" pot. Christmas cactus actually seems to enjoy being a little root bound, and will concentrate almost exclusively on root growth until they feel they've filled the pot to they're liking. It's best not to re-pot in the winter months if at all possible--spring is best time to 'pot up' as it gives you plant lots of time to fill its new space--but as we're down sizing our pot and you seem to be worried demise is imminent I would repot into a smaller pot right away. Christmas cacti are actually a jungle cactus and appreciate a good drink every two-three weeks or so in the winter (at least here in WA). I plant mine in a bromeliad mix with a little extra vermiculite for drainage. But if you are worried about overwatering (maybe you like to baby your plants) I would definately go with something with good drainage, poss. a good quality cactus and succulent mix. I also plant most of my jungle cacti in terra cotta as they breath better, I find. When you repot give your plant a good look, if you see any bugs (seem to get spider mites quite easily (little cobwebs--mites are so small that if you can see them easily you got it pretty bad)) rinse off the plant and roots and give it a good dose of Safer houseplant insecticide (it has a aerisol like sprayer on it and I find it easier to use)--reapply as needed. Then re-pot in sterile potting mix give it one good drink and try not to water it until it actually appears dry all the way through (2-4 weeks depending on conditions)--to keep from having the same issue again. Also, as a last ditch I would pinch off a couple of leaves of the new growth on the ends--to clone your cactus if it looks like it won't continue (christmas cactus are super easy to clone take the leaves you've removed and push the pointy end in some potting soil (smaller pot 2" is best) water once and don't water again until you can tug and feel roots formed). Hope this helps!

I wish to agree w/ the comment by LME, that the lower, older stems darkening is normal. This is called corking; it appears on the lower, older stems of these after a few years, it's absolutely normal, & not a problem. I'd suggest working on its recovering before thinking about blooming. In the meantime you can do a little reading. Search here for the link on 'holiday cacti', which has line drawings & explanations distinguishing the different types & their care. Likely it'll be fine given a little time. I'd also suggest a keeping it on a humidity tray, should help its recovery.

The pot it’s in is a glazed pot with an attached tray base with holes allowing water to flow out from the soil. I don’t let water sit in there. I do have the pot sitting on top of another tray which I fill with water. There is no way (as far as i know??) for this water to get into the soil because the pot is glazed and there are no holes through the bottom (they’re on the sides inside the attached tray). I read that it’s a good way to give the plant some more humidity. Is that not true? I like the glazed pot because it seems to hold more moisture than unglazed but not as much as plastic. The way I check the soil is just by touching it a bit below the surface. Is there a better way you’d recommend? Any ideas why the soil would look so old and deflated after only a year? I mixed in a significant amount of perlite. However greenclaws up above mentioned it looks “peaty” and sure enough i just looked it up and the base mix I used is mostly peat moss and peat hummus . What do you want in the mix instead of peat? I will look for an African violet mix. I have never found a good potting mix for this plant, I hope i can get African violet mix here. I would love to make my own potting soil but have not had luck finding the separate components. I felt lucky for finding a bag of perlite! It’s all just pre-made bagged stuff. Even at greenhouses. thank you all for your input. I wish I knew what was the primary stressor on the plant. Was it the direct sunlight? Sounds like the cold isn’t a big deal, and it wasn’t looking great even before it got cold. Is it the potting soil being all used up or whatever is wrong with it? I can repot and then put back in the room where it gets good light but protect it behind a sheer curtain. Does that sound like a good plan?

Thanks for the tip! I've definitely done some searching for powdery mildew remedies, but I also wanted to confirm if all the dead branches were caused by powdery mildew or something else. Does that sound plausible, or is there some other search term I should be using here? Sorry if this is a stupid question. I'm not a very experienced gardener.