Divorce Support Forums: Help

I did not know where to post this, so i apologize if it is not in the right place.

My husband has been divorced for 15 years (and has a 16yo child). You would think after this time things would be settled, but things are just beginning. She moved (with the child) and we have not heard from them Since August until Last week. Come to find out she is getting a second divorce and the child has moved in with a 20 yo boy. He is not attending school, however he has not "terminated enrollment" either. we pay $400 per month in child support, which goes to the ex. Can we go to court w/o a lawyer (we cannot afford one) and get the support terminated. i dont want him to move back in with his mom next week, and her say well you owe me child support again. I know c.s. stops if the child is a "drop out", but is he considered a "drop out" if he has not terminated enrollment. TIA, and sorry this is so long of a post