I had a similar situation to you, but I was married for almost 40 yrs.!
I don't know what the laws are in Australia. And if there are implications with you moving to another country I was divorced in the states ( which by the way have different laws even state to state ).

Anyway I also had no children involved. I had a signed agreement that we agreed on before the final decree. It had all the conditions of the divorce in it including spousal support.
She can " ask " for more but I'm not legally bound to give her anything more outside that agreement.

Here a judge ,or jury if it goes to trial , decides how much SS to give ,if any ! There are a lot of factors involved !

In the end I also felt I was more than generous. I basically left with nothing. She got everything. I didn't care , I just wanted out. I ******* hate the way marriage is so easy to get into but so hard to get out of. At least here in the US.
It's because of the $ involved.
They want it all.
TRYING to manipulate you ? She'll try and hit on your sensitivities as hard as possible.
Show weakness and your dead.

Watch out. That's just from my experience.