It is so tragic what happened with the fires in Australia. I can't even begin to fathom what people went through, and as for all those poor animals, dying by the thousands, my heart is breaking. To see it on TV and be shocked and saddened is one thing, but to be there and seeing, hearing, smelling and feeling the collective grief and loss is another one all together. I am so glad the rain came, i do love Australia!
I can't give you any advice, only you know what is best for you and your family. As you've said yourself: only one life! (And so very short)
What I can do is tell you that, in my experience, children are very resilient and will make friends wherever they are, they will adapt and the younger they are the better. What they do need is a constant in their lives, wherever they are, and that is your enduring presence and love.
As for being scared, who isn't? I am 70 and about to
sell my well established
Permaculture homestead and start all over again in a piece of very degraded
land. What the hell! Got to be mad, right?
Like one of your compatriot said in one of his famous film: " A life lived in fear is a life half lived." (Baz Luhrmann - Strickly Ballroom)
Whatever you choose to do, I wish you the best.