You might be able to take a 6" piece of 1/2" all-thread, put two jam nuts on one end, feed it through the hole in the hub from the left side (in side, frame side), thread a couple of nuts on the free end of all-thread, and use the nuts to clamp down on what's left of the hub. Clamp all-thread in bench vise and use a freewheel tool to remove freewheel.
Alternatively, drill and tap a series of hole in what is left of the hub, screw it to a plate or bar, put plate in bench vise, use freewheel tool to remove freewheel.
If neither technique works, go get a beer, sit down and stare at freewheel until you think of something else. Beer fixes almost anything.