That is actually the axle that the spindle is welded to. You may be able to have a welding shop replace just the spindle and have it reset in a frame shop. Truck benders can realign that axle if they are able to do I beam suspension. Though if you want an entire axle that can be done too. Since we assume you were headed home from Garry Wrights when this happened we also assume the trailer has sat for a few months. If so then the bearings took a set and probably rusted on one spot. Not sure what year model, though get a new seal for the opposite side if you are going with a new spindle in the opposing side. If it were ours we would try to just replace the one spindle and hub and not both for reasons of cost, though the decision is yours if you want a new axle. BCB