Wow, I've never seen a bulb with such a rotten basal plate. I think you are wasting your time trying to propagate it. I assume that you did get blooms, which is sometimes a one shot thing from a sick bulb. If you decide to try to save it, cut most of the basal plate off, dip in powdered sulfur, repot and see if the bulb recovers. At most, you have a 10% chance of the bulb recovering. This is something that most Amaryllis enthusiasts occasionally see in a newly purchased bulb. The bulb was already rotting when it was shipped. And after you've had it this long, it is basically impossible to get a refund for the purchase price.
