Hi Sam,
Im really sorry to hear about what you're going through & hope everything works out.
We have looked into moving to Australia several times over the last 10 years & each time we were beginning the process some family/ life event happened where we took the decision to leave things & stay where we were. In hindsite we realise that this was a mistake, although this is obviously personal to us & others would be glad they made the decision to stay.
We are now in the process of applying for our visa, although we are now in our 40s, my nursing career has moved from A&E to health visiting which I'm sure will make me less employable as I've been out of the hospital setting for 13yrs. We have 2 teenage children who I'm also sure will find the move a lot more difficult than they would have as toddlers.
The big difference is, looking at your timeline you are about to be granted your visa & that gives you a 5 yr opening to go.
You are stuck between a rock & a hard place as they say, but follow your heart & gut instinct as opposed to what you perceive others ( & perhaps yourself) think you should do. Sometimes in this life we need to be selfish if that's what will truly make us happy.
Good luck with your decision as only you can decide what is right for you.
Bigmac x