Hi John,
If you are holding a 457 visa, that means your wife also is holding a 457 visa, am I understand you correctly? If this is the case, your wife's visa should have a condition that she must have a marital relationship or De Factor relationship with you in order to keep her current 457 visa. If you do not want your wife to lose her visa, she needs to seek her own visa application before your file your divorcing in family court.
Most expat divorcing have some jurisdiction issues, but you can overcome this issue if you have been living in Australia for more than 2 years.
Hope this is helpful.
Ann @ expatlawyer.com.au