Question to your question...
You moved to Australia for a reason basically leaving your past behind while still keeping some ties to it. Does that reason still apply?
Can you really go back home to live for the rest of your life knowing you made your life currently in Australia? Would you end up resenting going back home restricting yourself for a joyous blessful reason when you could have done the same thing and still stay in Australia or where-ever else you decide as you please.
Something tells me Australia is your home now.
Have your child with a regular sperm donor and let your friend have a surrogate have his.