GreenHornet what I find ridiculously odd about this situation is that your JDub wife is praying for "God's" help in this serious situation. She is most likely praying for god to help this worldly surgeon so nothing goes wrong. Before the surgery, after the surgery, in her mind, all the doctors, all the hospital personnel will be bird food at WT's Big "A"... but just let god's holy spirit work on the hospital staff... so everything goes well for her.
Your exwife most likely is in well educated and experienced people's hands. I think one factor for JDubs going in for an operation is that they calmly (I hate to say, calmly but I do) relax because they truly feel if something bad happens, they will wake up in that promised panda petting paradise.
Every operation has satistics. Doctors want a successful operating outcome just as much as the patient does.
Reassure your children that their mom is not the first one at this rodeo and most likely, will be 99% fine.
When my ex had major heart bypass surgery, he was up and about in no time. A fellow elder, a nice man, at a different hospital, same operation, bled out in the recovery room and died.
Will you be there to support your children through this? Life with divided families can be difficult. I know.