Can it be fixed, yes, but its a lot of work. Take the bumper off, and Sand area. Use a heat gun to try and shape the protruding part back into the original shape. Use a wet cloth to push and cool the plastic down during the re molding. Once in the desired shape, your gonna have to use a metal staple gun to fuse the cracks on the back side of the bumper, then use a small grind wheel to smooth out the stitches. Once the cracks look sealed up, bondo the aggected area and smooth it out. Once the damaged area looks new, get it ready to paint. A body shop can to do all this, I'd expect to pay around 1K to get fixed.
It might be cheaper to find a replacement in all honesty.
2000 Mustang GT-Former giggle gas addict
1990 Mustang GT w/ Vortech V3
***resident gun idiot***