I have a CR1 green card that will expire in several months, can I get the definitive green card without my husband's signature?

You can remove the condition without your husband's cooperation.  However, you will need to file for a waiver based on divorce when you submit your application to remove the condition.  You will still need to prove that the marriage was bona fide when you entered into it.  

It is important to note that you will need to show Immigration proof of the final divorce order to qualify for this waiver.