It sounds like you have done a lot of planning, and there are no easy answers. Whatever happens, work together as a family. In a severe crisis situation, it would be an advantage to still have each other’s mutual support. High stress can tear families and marriages apart – guard against that at all costs, and resist the human tendency to see opposition as a sign of an enemy. You two have built a large amount of success over the years, apparently including two great kids. Keep that unit.
And yes – I’ve read about the requirements to get into Australia. From their standpoint it may make some sense, but it certainly is difficult for outsiders (which is probably their point). It makes renting a boat and sailing it across the Mediterranean seem almost like an option! (ONLY kidding!)