stancatts

Wow. That is a tricky one. Being married in Australia means that your marriage is subject to Australian law, which means if she is as cunning as you describe, she will divorce you under Australian law (make sure the divorce is under Thai law and hope your wife does not know the implications of doing it under Oz law). I think the kids are gone - sorry I know this is the hard part. Your wife has the possibility of the best of both worlds - financial settlement in Oz; and kids settlement under thai law (which means you have no say whatsoever about your kids). All you can do is damage control. First see a very good divorce lawyer in Thailand and Oz.  Then protect your assets in Oz from the Family Court. All you can do for your kids is pay for the best education in Isan (pay direct to school, not to your wife) and assume you will never see them again - there are good private schools there - and this could be conditional on your wife cooperating in some way. If you love your dear wife (hard to imagine why other than she is the mother of your kids), perhaps the best thing to do is go back to Oz, STOP giving ANY money to her, but offer to do so if she and the kids return to live in Oz. The only reason Isan is bearable for her is your money. She will blow what she has already got quickly and then perhaps she will be open to an offer of reconciliation in Oz. Don't think about whether she will <deleted> around in your absence because she will. You will just have to forget that infidelity if you want to reconcile in Oz. Best of luck. There are many lessons from your story. The first is keep your love life in one jurisdiction and your financial life in another.

They accepted my re-entry permit in my old passport, whilst stamping my new passport recently. That is important - they must stamp the new passport- but I understand that is standard practice.

But you will eventually have to get the re-entry thing at immigration and for some reason this is much quicker than getting the visa itself. I have been told by the staff at immigration (they were quite frank about it) that a stack of retiring Army generals have been installed upstairs to counter stamp the visas that the staff downstairs efficiently process, thereby adding 3 hours to the process. What a lovely golden handshake to the old Army fellas, who get high salaries and do nothing that adds value. Leaving the Army in power will lead to a lot more of this bullshit, but its not my country. Stamping by the generals upstairs does not happen with the re-entry permit, so its much quicker. 

why is Thai wine so bad anyway?

Thai post have an uncanny ability to detect money well disguised (2 X 1000 Baht notes) sent within a card sent from Australia with the Bangkok address written in English of course. Did it twice and both times the cards did not arrive - when I sent cards without money the cards arrived. I know Indian generic anti-hepatitis C drug manufacturers will not ship to Thailand - yet they will ship to Cambodia! i agree with the suggestion to register anything that you need to arrive - its not that expensive. Domestically, packages sent from one thai-person  to another and addresses written in thai with low value contents seem to reliably arrive.