Have someone roll your fender, they should be able to get that straightened out. Go to Hardware store and buy a J.B. Weld epoxy kit [10 bucks] Use thin strip of metal on inside to back it up. apply the J.B. Weld to the inside and use small vice grips or something similar to hold it together. After it's set up, finish the tear with J.B. Weld and sand , then paint. No one will know, it'l look great. That fender metal is thin to begin with, plus it's old, rusty and fatigued, I doubt if anyone will tackle welding it , for fear of making it worse, but there may someone..... that's brave. The other option, that I have done in the past was to Trim the fender a bit with a tinsnips or [ the way I like best] install a big mudflap on the outside of the fender.