Wow, sounds like your husband's sisters are full of self-centeredness. I'd suggest that you start talk with the Department of Health and Human Service's Administration on Aging:
http://www.aoa.gov/
You can find local programs, benefits and contact who can help you further. Be sure to search the whole site thoroughly, and call them with your questions. I hope that this helps!
Eldercare Locator : (800) 677-1116
Office of the Assistant Secretary for Aging: (202) 401-4634