I know the rotten look so well. I have been pulling some cacti now an then with the same rotten inside. Nasty look.
Some time ago I was watching some videos of people shaping Adeniums. They were basically cutting off the bottom part with roots and let the new rots grow from the sides only.
If it works on yours, it might look pretty cool.
Can't find the vid I saw, but this is very similar:
Looks interesting although I am a sissy, I can never bring myself to butcher plants like that
I would never do it to a healthy plant. Yours did it on it's own :)
Fingers crossed it recovers.