What does carfax have to do with being legal ?
Carfax is a private website, has no legal bearing whatsoever. It is not illegal to fix your own car, and there is no law that states accidents have to be disclosed. The only reason they ever would be disclosed is if an insurance claim is filed.
FYI, "totaled" is an artificial concept created by the insurance industry, and has absolutely nothing to whether or not the car can be fixed. If there's no insurance involved, a car cannot be totaled. Other people's ins. companies are very reluctant to total cars that are not their insured's. Either way, do NOT let them pay the shop directly, get a check written directly to you, and fix it yourself or get a shop to do it cheap. pocket the difference.
or just drive it that wat it is, and pocket all the cash. as long as it has headlights and a bumper, you're fine to drive it legally. if it drives bad, well then you might have other problems.