That's a tough question. I do know that when I was 11 I suspected my parents would divorce, primarily I believed because of a disengagement by my father of any real relationship with my mother.
My father did leave four years later and my mother could never understand why I seemed so unfazed by it - which I guess means that might put me somewhere in the situation of your kids, but with a different sort of parental marriage breakdown.
've just promoted (in another question) a yahoo group I am moderator for. I don't mean to hijack this website's forum - as this is an excellent website with excellent information! (and we do link to it from the yahoo group!) Nevertheless, the group has many *very* active Australian members. You may find furhter support there.
Chris (youcantryreachingme), Moderator for the online yahoo group "giftedfamilies" which is open to all but has a strong Australian flavour. You will need a Yahoo account to join, but you can read the group intro without a Yahoo account.