Oh, Poor old girl! My opinion is that there is no coming back from that. Hopefully @casportpony will give you a second opinion. If she is no longer able to pass poop and her crop is backed up, I would say she only has a matter of a couple of days at the most, probably quite a bit less. Give her a nice blow dry with a hair drier (assuming she enjoys it) and keep her warm until you can make arrangements to end her suffering.