The IRS will not tell you anything about your husband's tax return unless it is a joint return. You can always call the IRS and ask them if you have filed your tax return for the year in question. If they say yes and you did not file it then it is likely that he filed jointly. Just keep in mind that the IRS will not get involved in any disputes over refunds so if you want your share of the refund you will need to address that during your divorce proceedings.
firstname.lastname@example.org Office number: (860) 255-7423 Website: www.cttaxhelp.com. Our reply to your question has not created an attorney-client relationship. It should not be considered legal advice. You should contact an Attorney who can give you legal advice after acquainting themselves with the specifics of your case.
Your lawyer can find this out. If you do not have a lawyer, go in on a motion to compel him to file jointly with you. Also, check with Avvo's immigration attorneys who are conversant with the tax laws.