My son is 18 years and 9 months. He is working, earning a wage, and living in an apartment outside of his mother's home and even state. Do I continue to pay full support for this child?

What does your support order say. Usually the conditions when support ends are spelled out in the support order.

Every support order is different and some very strange at times. Normally if he is not going to college, and living on his own, no you would not, but your case is decided by the written child support order in place though the court