I have a 2000 Pontiac Firebird it has 83,000 miles on it and I bought it full in cash. It did have a rebuilt title however

I got into a minor accident and the fender had damage. Instead of making the insurance company pay for it (didn't want boost in premium), I decided to pay for it out of pocket. I took it into the shop and the repairs were estimated at $2596, When they took of the front end, they found that the "Radiator Support" was smashed on both sides and needed to be replaced, I said.."Ok...might as well"...that boosted the price to $3895....NOW...He said the car has been deemed "unsafe" to repair unless I got a whole new "Front Clip"...and this would raise the bill over $6000...I told him that $4000 is the highest I want to go, but he KEEPS insisting on trying to find something....Now if he doesn't fix my car and it is still deemed "unsafe" do I have to pay for the car, or can I just give him the title and call it a day?..Better yet, can I just give him the title now?
The Radiator support was smashed because it was in a previous accident and the people that sold it to me before did not fix it properly. I REALIZED IT AFTER THEY TOOK THE FRONT END OFF.

The Radiator support was only $600 the labor is what is killing me.

He also said that he cant hang anything on the front because of the way the radiator support was so badly damaged.

The reason why I am considering not paying for it, is because I dont want to pay a ton of money for repairs.