I have some bad news.
The the whole tailgate needs to be painted. Then the paint needs to be blended with the sides. All the hardware needs to be removed from the tailgate (including the glass). New emblems need to be put on after the job is done.
To do it right (indistinguishable from the original, with just the right amount of orange peel in the paint), you're looking at about 3K.
I am a part owner of a body shop that does show car work, Barrett-Jackson cars etc.
You can have it done much cheaper, but the quality will go down accordingly.
The best way to do it, is to report it to the insurance, take it to the best body shop in town (the one your BMW dealer is using), pay the deductible, and deal with a possible premium increase. If the insurance company gives you a hard time afterwards, you can always shop for the new policy.