It does not matter if you are still legally married or not, if you have been a permanent resident (with a green card) for at least 5 years, you can file for citizenship without your husband's knowledge and without needing to still be married to him.  However, if you have not been a permanent resident for 5 years yet, and you are no longer in a bona fide marriage, then you need to wait until you have been a permanent resident for 5 years.