Can my 12 yr old dead beat son father get custody and support from me, how can I get full custody

He is 15k+ in arrears already, last year my 12 yr old son got out of hand, asked to go live with his father, my oldest so got the father a job working construction. He then went to going to the dope hole every weekend until he was laid off from the job. Lost his place to stay with his mother in Pt.St. Lucie, moved to Jacksonville with his older son, planning on working under the table again. Wants child support because I told him he could not come to GA and lay up on me