Please tell us about what will happen in terms of college. I do not know the system in Australia - do you pay for college, how much, are their scholarships and financial aid, grants from the schools and/or from the government, etc.

Since the kids are 19 and 14, and since the only issue is money (no, you do not come across as mercenary - you come across as sane and realistic), that part seems to the most important part in terms of planning for the next 10 years.

Also, his plan to live his life to the fullest is undoubtedly great (for him), but would the courts in Australia allow him to do that? Some courts in America, if you start earning less than you did and you owe support, will tell you "OK too bad, we will impute wages to you and calculate support obligation based on IMPUTED rather than ACTUAL".