Owe back child support but pay lump sum

by J.J. Johnny
(Arizona)

Hello my situation is that i was paying child support since 1994 but not through the child support office (didnt know i needed to) straight to my ex and taking care of medical etc. she was a drug addict and lost custody (Child protective agency) for some reason they gave custody to the grand parents , and not me?
so i have no idea who was getting the money she moved and my son stayed in Arizona with grand parents( i had no money for lawyer) i
know i should of hired one!
then she moved out of state with my son with no permission, she was married to a heroin addict w/ two other children.
she has always skipped around my son is now a drug addict at 16 and has no supervision, ive asked the "child support enforcement" if they will do somthing about this with no avail.
so now im $29,000.00 in arears, w/ onlt $11,000.00 princable and $19,000.00 in interest and i have paid, well they have taken $2,500.00 or more a year from me and my son and family with two other children.
not sure what to do but would like to get this taken care of as im trying to inlist in the national guard and getting a position as a prison guard.
so "money hungry drug addict dead beat moms" there is no excuse for you when there are fathers out there with there hands tied!

SOMEONE PLEASE HELP ME!!!