Child support.. In not sure where to put this..

My SO has a six year old son.. That he has to pay child support on. I understand the whole thing of pay child support I have a four year old daughter that her dad is ordered to pay but does when he feels like it.. Anyways how would you feel if you had to pay child support but it does not go on the child?? We buy his son everything.. We had him from 530am til 5pm from sept 2013 to school started this school year. The whole time the mother was getting child support and food stamps on the child all tho we feed him. Yes my SO lost his job and fell be hind on a few payments she took him to court and he now has to pay 1513 dollars or do two weeks in jail.. He tried to tell his lawyer and the judge this but neither listened.. How would you feel and what would you do?? I'm really upset about this because we do so much to help her out if she calls and needs something we get it and take it to her.. We've even watch her other children that are not my SO kids..