Everything Was Going So Well.....Until It Wasn't

Really sorry this happened to you. Hopefully it won't be that tough to repair. New rear suspension components and perhaps some frame repair. Align the rear axel. Fix the exhaust.
I came close to something similar with the camper on the truck. It was on a near flat street but thick wet ice beneath made us slide like a curling stone. We barely made the left only turn without hitting anything at the end of the street.
Best wishes for a speedy repair.