Heart broken

Almost any severity of damage to modern cars is repairable and totaled is when the repair cost estimate exceeds the appraised cost of purchasing a similar or identical mileage make and model with whatever options the car has.

Since it was the back of the car that was damaged your low mileage engine/driveline is probably as usable as it was before the person crashed into you.

Most insurers will sell you back your totalled car for its scrap value if you tell them you want to keep it for the remaining good parts.

Then you can find another exact same year as yours with a southern rust free chassis but higher mileage that you could negotiate a very inexpensive price to buy and have a mechanic place your driveline into that one.

The cost of swapping out the driveline and buying your wreck back and another car like your own should be in the vicinity of your insurance settlement plus or minus by a small amount.

I wouldn't talk about that to the person who said your car is totaled. He may be jockeying to buy your wreck to get his mitts on your low mileage driveline. Talk to someone you already do business with for vehicle service and ask them their fees to switch the engine and any other things in your car, black leather seats, etc.

There's a solution. You just haven't been told it by anyone. And the body shop not suggesting it seems a bit lazy in my opinion.