Punkin, I can understand your frustration. And it's not uncommon to take out our feelings on those folks who are closest to us. Your son sounds like he would be a challenge to anyone.
Is there any way you can see your therapist more frequently? You could talk more there, and also this person might have some suggestions for other resources and programs. I gather there is no support for you--from spouse, parents, friends, etc.
Do you need some suggestions for how to deal with your anger? I have some ideas.
Are you able to be in any contact with other parents who have children with some of the same issues?
Please let us know.

We do care.