Dreadfully sad for you but you did the right thing seperating them. If the other one doesn't survive, well you did your best.as you can imagine, I was forced to tie off the shared umbilical. This resulted in the immediate death of the smaller twin (presumed shared heart?).
I then cut away the umbilical on the smaller twins side and treated with antiseptic. The bigger twin survived this, although, two years later, it is clear that it's growth has been affected- it is smaller than it's two other siblings, and it suffered some calcium deficiency, resulting in some minor but disfiguring deformities.
This is only the second time I have had this happen, in over 25 years of breeding, but even so, very upsetting.