First you need to get him out asap before they do charge you with abandonment. I am sure there has to be some in home care places for you that nobody seems to want to help you with.
Ask them about Respite that is one that should be provided to you.
RCCCWA Respite Resource Guide - Washington State Agencies
They wouldn't tell me about some of the programs either. Actually one program they didn't tell me about pays you to care for your disabled family member at home. I don't know the name of it.
Have you checked with Social Security they should be able to tell you programs that will help. Also you should be able to collect disability for him, somewhere around $600. A month. Have you done that?
If you do not pick him up as soon as possible I do not know about charges, jail time or anything like that but I DO know they can come after you to pay them child support and take away your parental rights so you won't be able to get him back until he is 18 -21.