You will have to remove the hub, then disconnect the upper control arm either at the ball joint or completely from the car, then the spindle. You put the spindle in a vice and beat the remains of the lower ball joint from the spindle using a hammer and a drift of some sort, usually a large socket works pretty well.

I would be concerned that the lower control arm or possibly even the spindle could have been tweaked if either encountered enough force. Maybe the lower ball joint was ready to fail and it didn't take much but from the description you hit pretty hard with the entire force of the moving car behind it!