Not sure what to do
I understand the shock and confusion you must be feeling right now. It’s not easy to process. It seems you have two issues to sort through. The first is your marriage and secondly access to your children. From what you write, it appears your wife has decided the marriage is over. If that is the case, there is very little you can do about it. You can’t make a person love you and want to be with you. I know this a terrible kick in the guts, but all you can do is be the best version of yourself that you can be. If your wife one day changes her mind, well that’s a question for another time.
My advice is stay calm, friendly and polite with your wife. Ensure you eat well, exercise and lay off the grog. She is the mother of your children and her attitude is crucial when it comes to working out the children’s futures.
Of course, you do have legal rights and you should seek professional advice as to what those rights are. Bear in mind, the law can’t please everybody and you may have to have a flexible attitude, that may hurt you emotionally in the short term. Perth is a long way from Sydney and if you stay living in WA, obviously regular access is impossible.
Many men (and some women) reading your post will understand the pain involved in having the double whammy of losing your spouse and your children so suddenly. You will survive this and eventually work out a plan with your wife to sort out the future.
I wish you all the best of luck.
You can't just move the kids interstate because you feel like it.
File a relocation order through a solicitor and have them returned.
Too many fathers just allow mothers to dictate the terms, it doesnt work like that...you have a right to be apart of there lives