I think you should find a lawyer quickly. I may be mistaken, but my understanding of "Section 8" is that the tenant pays rent equal to a percentage of income, and that's supposed to cover everything including utilities. If I am right you were supposed to supply utilities as part of the rent arrangement as the government is supposed to be subsidizing the situation. Did you ever think of going to the federal building or calling Peoples' Gas? In fact what you may have done is given her the right to declare a constructive eviction, and you may have committed an illegal eviction. Plus there is the Chicago Residential Landlord and Tenant Ordinance to consider. And if there are children in the apartment, oh my. Time to find out what your legal obligations are. Good luck!!