You can certainly try and cut till you see clear no decaying part, and let that area callus, before sticking to a dry gritty media, so it can try to regrow new roots. But be patient, it takes time. Position in part sun/shade till it manages to show a new well formed leaf again, before you can resume watering. I do not know how much will be left on your cutting, if it is enough energy for it to go for, but always worth a try. It may still try and catch up.
