Ex is consulting surgery for our son?

Outside of the other advice you also need to have a court order asking for a halt on any surgery not deemed in case of life or death requirement. I would also suggest you file a motion with the state medical board where you live for same reasons and requiring the medical persons in question to state the needs of such an operation and why you were not consulted. Do these measures quickly. If possible find out the hospital or medical clinic where they intend to perform this operation or procedure and make your presence known.