The bottom stem is green

Im assuming you killed it via overwatering? That is a pretty big pot for a plant which im assuming has little to no root system. I havent tried this with a thanksgiving cactus, but if it were me, I would cut it back. Maybe two nodes back from the tip? Then I would stick the cut ends in water and let them perk up. Sometimes it takes a day or two. If they dont perk up, they are probably dead. But after giving them a drink, I would stick them in the pot next to this one so that they can root as well.

There is some hope, but you definitely need to change some things. First, get a 2 -4 inch pot...your current pot is way to big. Second, you will either need to cut your current soil with at least 50% perlite or get some really small pieces of orchid bark to replant in.
Get as much of the old soil as you can off what root system there is and plant in the new pot and mix. If there is no root system, I would lay the plant on top of the new mix and support the plant as best you can.
If there ARE roots, let the plant sit for a few days, then water until you see water coming out the drainage hole. If there are NO roots, then I would daily mist the end where the roots will grow.
Do not stick any part of the plant in water...you will hasten rot.
If you want to take a few segments off, you can do as I said above and lay the segments on the new mix.
Keep it out of full sun; give it bright shade. These plants grow in the crotches of trees up in the canopy and receive filtered light through the leaves of the trees they live in.

Good luck!

Nancy

Thank you very much Nancy. I will try it.
I think I overwatered it. The plant is now in its third soil. I have been trying to fix the problem. I did have too much water and drying out problems with soil that it had been in. I think that I had made a mistake and it was just in the wrong soil. Right now it is in Hoffmans succulent and cactus mix and I had hoped it was doing better. It is holding the water better. One of the soils that I had it in was an orchid soil. I still had drainage problems.

Hello!
I have a bunch of these cacti and I can tell you several things that might help you:

1. These babies usually turn pink/purple/red like that when they're in too much sun. The colour is a sign of stress. The leaves should be mostly green or all green. In my experience, a little morning or afternoon sun is good for them, but more than that can make them unhappy.

2. These plants are epiphytes that naturally grow on tree branches, so they have very few roots. Your plant will need a much smaller pot, as brodyjames says.
Also, if you're having trouble getting the amount of water right, I've had great results growing these cacti in pots of pure sphagnum moss! The moss acts like a sponge, sopping up excess water and keeping the plant moist. Just try to keep the moss damp.

3. These cacti do not like a lot of fertiliser. They do need some nutrients every now and again (especially if you grow them in a nutrient free substrate like sphag moss), but if you follow the directions on a standard packet of fertiliser, you'll end up giving too much.
They only need a diluted feed once every couple of months at the most.
If you think you've given your plant too much fertliser, run fresh water through the pot for a few minutes to flush out the soil.

I hope your cactus improves!
These are lovely plants and can be very rewarding to grow! (:

No one is really zeroed in on the problem except Nancy.

I believe it's the mix you're using it looks like mostly peat, which hardens after drying & becomes near impossible to re-wet. So while one waters & waters, the rootball doesn't really take in the water 'cause it's rock hard & water repellent. Does that mix feel hard to the touch, bit like a brick?

Most folks grow these in plastic pots (not clay), much smaller as mentioned above. Like a 3" pot for that ONE cutting. About the mix, one doesn't want it to hold water, but to drain almost immediately. When one waters, one waters 'til it flows out the bottom of the pot, give it a few minutes & then dump out the excess water.

I use African Violet mix w/ extra perlite for these. Cactus & Succulent mix (C&S) tends to be too heavy for them, but added perlite can remedy that.

The person advocating keeping them moist lives in the Tropics. Unless you do too I wouldn't do that, here in the US, that's likely to cause rot, the exception to the rule might be FLA.

Nancy's given you good advice, that should help it get better.

Thank you all for your terrific help. I live in central PA. I guess that you can tell that this is my first cactus of any kind. After you water do you let the plant soak for 5 minutes? Should you ever spits it? I am glad that you mentioned the sun because it has been outside on a covered porch but getting sun through sky ligths so I will move it away from the sky lights.

If a add perlite to the cactus soil how much should I use?

If I was growing a Thanksgiving cactus in perlite/soil, I'd make a mix of maybe two parts potting mixture to one part perlite. Or even 1:1 mix and perlite, if you like to water often.

I live in a temperate climate, not the tropics, but I do grow most of my plants indoors, I'll admit.
I have never had a problem with these cacti rotting ever. I've had my oldest one for ten years and right now it's covered with flowers (it's winter in Australia).
Any loose mix which allows the roots to stay well aerated will do for them, in my experience. I have found them to be extremely non-fussy about their substrate (my old cactus is in 100% regular potting soil), though they grow faster when the mix is loose and not compacted.

Still, I know everybody has their own way of doing things. You've got to find a method which works for you personally and fits with your watering regimen.
Since I use water retaining mixes for most of my cacti, I only water very rarely. I have loads of plants so I'm not tempted to water more often than I need to (no time! LOL).
I certainly wouldn't advocate growing any plant in unadulterated peat moss, though, since it does set like a water repellant rock.

All the best,
Sparkey

Oh, as for watering, just give it a normal drink with a watering can, like you would any other plant and don't water again until the mix seems pretty dry.
This cactus won't need misting, but it's good to give the plant a shower every once in a while to clean the dirt or dust off - it'll look prettier too!

- Sparkey

it's been overly hard grown and difficult to ZERO IN to any one particular problem as there is more than one problem to contend with.

Lighting: to strong for to long which may have caused the OP to
Water more heavily than they may have had to
One word for the problem ....... OUCH

Problem one : The top of the plant has been dehydrated At this point PLEASE don't water the pot.
There is some hope but the recovery road would be a bit long.

Problem two: It'll need to build new root as you remove it from the old soil In my opinion it may take a year or longer to return to any normal growing

I don't think there is a need explain in detail(s) how to discuss recovery suggestions if you are going to replace it with a replacement plant ( Which is also an option)

Problem three soil: Looser more airy than what you have ( bark based) but as mentioned no need to suggest a soil if replacing it.
Tropical jungle plants soil suggestion(s) could be discused to you on a different thread by you if replacing ?

Problem four : Understanding Internet instructions and/or real life suggestions in the event of more than one opinion or suggestion(s) can be conflicting.

No gurantees is all I am saying

Thank you very much for all of your terrific advice. I ordered Perlite and am waiting for it to arrive. I am going to cut and repot too. Then cross my fingers and wait. Waiting can be hard. I may replace next yr. now that I know more about them.

Sounds like you're on the right track!

And don't worry about the cactus. Just looking at base, I think it'll regrow. I inherited one from a neighbour which was so shrivelled I thought it was dead, and after a few months of care, it perked right up. Now it's gorgeous!
I think these plants can be confusing, because their requirements are so different to other cacti. Not many other cacti naturally grow in trees in tropical rainforests...

I really hope your cactus recovers (:

- Sparkey

Hi Suzy,

For additional reading on these if interested, pls. switch to the Cactus & Succulent forum (these are tropical cacti). There, you can either browse or search for Holiday Cacti, which covers both Thanksgiving & Xmas cacti, which are closely related & take mostly similar care.

There's a great deal of info. there to be had, which you may find of interest.

It may also help you see folks make a variety of mixes for these, all needing to be fast draining & growing the plants in bright but indirect light. Good luck.

I grow mine in orchid bark. They love it.