As usual, there is no getting around it, for a plant with root rot, the fastest way forward is to take cuttings and restart the plant. Even after all these years, I try to kid myself into thinking that I can get away with a re-pot. Hoya sp. RP-013 languished, and did absolutely nothing in that terracotta pot for literally months until I relented, and chopped it up into one node cuttings. All of those cuttings now have new growth. So people, if you take nothing else away from here, keep in mind that root rot means start your plant over from cuttings if at all possible!