Hi Rachel,
Tracy is correct that you have an obligation to notify DIBP of changes in circumstances (generally within 10 days of them occurring).
If DIBP becomes aware that your husband is not longer working for his sponsoring employer, and he is offshore, they can cancel his visa at any time without notification (no notification is required where the primary applicant is offshore), though they would generally allow him the standard 90 days to return to Australia if he chose to.
Once the primary applicant's visa is cancelled, both your and your daughters visa will be cancelled, but DIBP would contact you first to check if you have made arrangements for another visa or made plans to leave Australia.
If you have an Australian partner, you could consider lodging a partner visa with him if you can satisfy the criteria and have sufficient evidence. A divorce is not necessary to make a partner visa application (though it would be required for you to re-marry), but you will need to show you have separated from you husband with supporting evidence.