Go to U.S. Consulate if your son is a U.S. Citizen and you are a green card holder for assistance in getting a travel document of your son.
Unless you have a Conditional LPR, you don't need your husband to "update" your greencard. Even if you are a CLPR, the actions your husband has undertaken are abusive and there are going to be options for you.
You need to consult with a good immigration attorney to talk this through. This is clearly a complicated and sensitive issue. It could cause complications for your husband.
Ricky Malik, Esq.
I believe that it usually requires both parents to appear in person or apply for a child's passport. If the other parent is not present, he or she would need to sign a notarized Statement of Consent, Form DS-3053. You have a unique situation because I don't think the father will consent. Check with the US Consulate if there are exceptions.
Another option would be to enter alone to the U.S. and file for separation or divorce with sole custody of your child so that you are allowed to unilaterally apply for a passport. Also, if you are on a conditional green card, you can apply to remove the condition with a waiver as long as you can prove you it was a bona fide marriage and you did not enter it to obtain immigration benefits. Contact me if you have any further questions.