Child support when Ive been doing everything?

My childs mother has her mother, a grown brother, and her 9 year old son living with her. I am on house arrest pending trial for an unlicensed weapons charge. We have a 6 month old son that I have 4 days out of the week (sometimes more). She pays her rent with a check that she recieves (illegally) from her first child. She also recieves Wic for our baby, and Food Stamps. She has been recently diagnosed with a minor Cancer, and cannot work. I have been doing everything even from house arrest, with the help of my family, but, now she is filing for child support. Her Mother doesnt work, and her brother doesn't work. If it werent for them, she would not be in such a bad situation. If I am ordered to pay child support, and I end up doing time in jail, will I owe back child support when I am released? What can I do to curtail this? There is so much moreto this story (I'm sure you've guessed). She has two other children whom she doesnt have custody of.