Thank the airbags all you want, they had little if anything to do with your survival. Thank GOD you weren't 0.5 seconds ahead of yourself or they weren't 0.5 seconds behind. You could have truly been t-boned and likely dead or in critical condition, and the car would be worse off than you.
I hope you can work something out with insurance. Sticking to your guns is your best weapon. They will lowball you at every step and drag things out to force you to settle out of desperation. If you have receipts that certainly helps, but they are literally going to throw the book at that car. If you want it repaired or receive a reasonable payout, you have to prove the car sells over book. Start hitting up all the autotrader type websites and build a physical portfolio by printing the listings showing it's worth $8,000 not $2,500.
Unfortunately, I think it will be totaled too. Even valued at $10k that looks like "more than 50% of it's value to repair", and I'll never forget when my friend had his 6 year old Ford Ranger backed into. All that happened was the fiberglass bed got a hole punched into it by a ball hitch behind the rear wheel. Minor cosmetic damage only. They said it was "totaled" and offered him $1,200. ...for a near mint pickup. He told them to F*off, and got nothing for his troubles. We repaired it for $20 in materials, and he had that side of the bed painted for $200. ...so, $250 in damage. Even a replacement (salvage) bed would have been $500 tops plus paint, and the truck was worth at least $5k. We think they wanted it for parts.
...point is, don't trust insurance adjusters, their job is to save the company money, not help you. They employ different tactics designed to break you, do not give in until you feel the offer is at the very least a fair one.
I'm hoping the damage isn't as bad as it looks even tho it looks bad. I can almost see myself repairing that, but I can also almost see what I'm not seeing which does make it "unworthy" for repair. That said tho, many cars that were once junked for their unworthiness are now being rescued and rebuilt so they weren't really lost causes afterall, the value-to-hastle ratio was just low at the time. ...and you've seen what some members have brought back from the dead just out of love for the breed.
Worst case is probably keep the car, accept a small payout, and buy a cheap broken v8 'bird or a cheap but super clean v6 'bird and use yours as a parts car or donor vehicle, then part out what is left over on Craigslist/Facebook Marketplace, and sell the body to the salvage yard as scrap (or have them just remove it for you). What you do have in your favor is the fact a blown head gasket repair, or a rebuilt transmission exceeds the book value of the cars or at least eats up half of it. Best case, you get enough to buy a comparable Firebird. Middle of the road, they repair it, and you have to wait and fight quality issues.
Glad you're all OK after that, I just hope the world hasn't lost another 'bird.
Best wishes and best of luck to you.