The value is probably diminished regardless of who did the work. Since you were at fault in the accident, I believe there is a clause in your insurance policy (this varies by state, so don't quote me!!) that prohibits you from making claims on "diminution of value" upon your own insurance company.
Unless you could prove that the work was not done properly, I think you are out of luck.
As your car ages, the diminution of value will not be so great as it might be now. The best thing you can do is keep good records of what was done to the car, and show that no serious frame damage occurred, and this may help to alleviate the fears of whomever you sell the car to at a future date.
But the short answer is, yes, on the face of it and without providing info to the new buyer, your car's value is probably 25% less now. In reality and in time, it might not be so much.
You should also check if you can make a diminution of value claim against your own insurance company. I rather doubt it (you could if someone hit you, however, since you would make the claim against THEIR insurance company). So check that out.
If you CAN make such a claim, get a professional appraiser to appraise your car and estimate the diminution.