Any help to pay medical bills should have been obtained before your husband died. However, it may be impossible for any creditor to forcibly collect from you unless you have assets that are not protected under your state's exemption laws. I am posting a link to a general description of these laws for you to review and would urge you to get additional information directly from the state laws themselves. Hope this perspective helps!
Go speak to someone in your local legal aid office. While you might be responsible for some of this debt, you do not have the money are are basically judgment proof...A creditor cannot touch your disability money.
If he passed away at a hospital, the hospital may have qualified him for some kind of assistance. Just a thought. If not, you could be in for a lot of collection letters because spouses are liable in Illinois for necessary family expenses including medical expenses. You may need a lawyer on your side.