I actually just had this same problem only I stripped both front flare nuts for the brake lines. I too panicked and wondered how to replace the whole thing until I found this magic tool:
https://smile.amazon.com/gp/product/...?ie=UTF8&psc=1
It's a stupid price for a simple vice grip but it works. Clean the threads with brake clean and a brush if they're not already clean, heat the nut as hot as you can get it without melting the fender liner, spray penetrating lubricant on the threads after they're hot, and then clamp it with the above wrench and it'll come right off. Save you some headache having to swap the whole line.
Good luck!