I would agree that the white could be urates, but that doesn’t look good at all. The mass inside could be lash egg material or a tumor, but hard to know for sure. A lot of things may become more clear if the hen dies, and a necropsy could be done. I hope that you don’t lose her, but it does happen.
It is possible for a vet to put a stitch or two in the vent to hold the cloaca in. But since she may have been pecked or damaged from too large of an egg, this could happen again. It may take awhile for her cloaca to stay in. A lot depends on how much time you have to deal with this, keep her...