As long as the eye itself isn't damaged(which it doesn't appear to be in the picture) and there isn't a split open wound(which doesn't appear to be the case), then in my opinion it should be fine to heal on it's own, though if there is a cut I might apply a very light layer of plain triple antibiotic ointment(no added pain reliever) just to ward off an infection starting. If this is done, it's good to distract them with something like eating so they don't immediately try and groom it off.
If you think the eye itself may have been scratched or the wound is split open and would need stitches, then yes, you would need to go to your vet.
I'm sorry this happened. By all indications, I would have thought they were close to being bonded too. They certainly were both acting like they liked each other. Though keep in mind that even most bonded rabbits have humping and the occasional scuffle going on. My rabbit Penny, has been really grumpy lately and is constantly going after Henry and chasing him off, yet is also very happy to snuggle up to him at times. I would imagine that if he didn't run away from her that he would get bit or even a scuffle could occur.
The extra skin will fall off with time, and she should be good as long as it does not get infected. Poor baby girl, she is so precious. Bunny fights are the worst 
