1. Don't worry, Centrelink will help you, without there being any negative impact on him.
As a PR, you have the same rights in this area as a citizen.
It doesn't matter if you are married, or not married.
Centrelink has no ethical or policy opinion about the how and why of how you got pregnant.
And any trouble he has with his wife, that's on him.
2. You don't have to have a termination. No matter what he might say.
Continue the pregnancy, or don't. It's your choice.
And nobody else gets a say on that in any respect.
2a. Adoption remains an option. Your choice.
Extensive counselling happens first.
3. Yes, he has to pay Child Support. No matter what he says.
Even if he never meets or sees the child.
And he doesn't get to attach conditions to it
(so none of this "I'll pay as long as you don't tell anyone" stuff).
4. If you don't want him in your life, then that's your choice to make.
He doesn't have any "rights" here of the kind men often think they have.
5. If everyone involved in the sex that got you pregnant was consenting at the time,
then he will not get into trouble with the police or immigration.
And no, he won't get to (or be required to) stay in Australia
just because he has a child with a PR.