I had a bearded dragon with MBD so bad he couldn't move any of his limbs or even lift his head up and I almost gave up on him. He hung in there though and so did I. Today he's a very fat beardie eating up superworms faster then I get hand them out most days. :^) You tough it out Sweetpea!!!!
What a cutie she is. MBD can be treatable, however, it is a long and winding road to reach full recovery. Bones will mend after time, however, any outward signs, such as lip curling etc., will most likely always be present. Those are just cosmetic things though.
Hang in there, keep giving her the treatments that the vet recommends, prepare to have to give her tender loving care during the duration of her recovery and know that you can help her get back to being a strong and healthy chameleon .
I have seen chameleons recover fully from MBD with success if caught in time and given good treatment.
She really is cute!
EDIT: PS: I didn't see your vet recommended putting her down. Did he give you any regiments and/or medications to help her through this besides the recommendation of putting her to sleep?