Echoing what Susi said......
If your son has a caseworker there are plenty of people they can hook a kid up with. They actually get paid to spend time with your kid. If you don't have a caseworker then look up things like a shadow (with your school) or a BI (behavior interventionist) with a local foster kids office. There are people who can be paid through Medicaid.
Here the Big Brothers/Big Sisters list is sometimes long. So many kids needing a parent or a buddy. If you aren't sure what you're looking for PM me your town and the nearest big city and I'll do some research for you, BUT I would start with resources like: The school counselor, the United Way, Catholic Charitys, Lutheran Family Services, and belive it or not some towns have policemen that actually take kids a couple times a week and train them to be Jr. police. Yes.....even difficult child's with ODD.
As far as his father not "wanting" him. been there done that. So you have your son in counseling right for his self esteem, so he KNOWS and figures out on his OWN that he is more worthy than to worry about why his dad isn't there for him?? That's usually free through your local Mental health - which is another resource for a big brother.
Check also your local WHAT"S happening and get difficult child involved and keep him busy as you can with local art groups, or whatever is available in your neck of the woods. We're here to help if we can.
Hugs
Cyber Aunti Star