Thank you for asking this question. I'm sorry that you're in a position to be asking this question and for the experiences that you've had to go through.
This is an older post so hoping that you are still around and browsing the forums, but I did want to pop into answer your question.
If you go to this website https://psychology.org.au/find-a-psychologist you can filter through issues and a location. If you click on the tab Trauma / Harm, you can then click "cult involvement".
I hope this is helpful; or that you've been able to find someone since asking here.