Did you not use the heat? That is the trick. You tap and heat the lug and she'll break free. With a rusted/fused nut, over powering it with brute force leads to snapping. People do this with water pump bolts all the time. Once the first one snaps they should go get the mapp gas but instead they keep going and break ALL the bolts
If you have to have the lug cut off I would just spend the $50 and get a new hub rather than wasting the time having another lug put on the old hub. You'll get new bearings and races and sounds like it's due for it anyways.