Sorry to hear you got wacked. Hope they have insurance. Try to find a reputable shop to get the repairs done. They will probably have to replace the whole rear axle and pumpkin internals. Since the axle probably pushed into it and popped some things apart. Just make sure when you get it back that you see the slip from the alignment. If there is no slip, don't take it. You want it to be totally finished before taking or you will run into problems getting things taken care of. Someone else had his Frontier worked on and once he took it back the insurance said we are done, you need to work it out yourself.
Just a word to the wise.