Fraud: Suspected Program Violation for Food Stamps

My question involves criminal law for the state of: Missouri
Received food stamps 2010-2013. Ineligible in 2013. I thought because 3 of my 5 children no longer live at home. But it was because my income was not considered for eligibility. I had given all income paystubs, my children would even take them with the paperwork to drop off. What does "suspected" mean? All I can find out is Intentional program violation. My letter came this month stating the above. In the amount of $24,000. I had no idea my income was not included. The letters came from Investigation claims unit but latter also states I may be contacted by the WIU , welfare investigation unit. I fear the worst and I am terrified as this was in NO part intended. I am requesting a fair hearing and have applied for legal aide as I am only one working. The more research I do, the worse I feel as there is NOTHING showing a positive outcome. I am also writing to my senator and representative. What can I expect? How long is this process?