According to the Migration Regulations, you can still be included in the 887 visa application for permanent residency, as long as your ex-husband is happy to include you in the application. You can be divorced and still meet the criteria for the new visa as you hold the old visa granted on the basis that you were a member of the family unit of a person who holds a visa of the same kind as the old visa. Obviously, your ex-husband needs to agree to this, but it is definitely possible.
What happens to the status of a dependent who separates from a 489 visa holder?
My husband and I got our 489 visas of Australia, with my husband being the principal applicant. We recently decided to get a divorce. Will I still be able to apply for permanent residency of Australia after the divorce?
Unfortunately, as this is a provisional 4-year visa, you will only be able to remain for the period of the visa validity. However, the principal applicant has an obligation to advise the Department of Home Affairs of a change in circumstances, which could lead to the department canceling your visa.