saving a plant

I've had a jade for several years now. I bought it as soon as got home from Grenada. It's gone everywhere I've gone. Sadly, last summer I left it for a couple of weeks to go home. That's usually OK. It's a succulent and they don't normally need much water. But when I got back I noticed that it had been ravaged by a fungus infection. I trimmed it way back. But the infection didn't go away. So I kept clipping and clipping. At the end there was only one leaf. I still have the leaf. It sits in a little limoncello cup that's now encrusted with calcium. Tiny delicate roots grow from its tip.