Oppositional Defiant Disorder (ODD) Support Group
Oppositional Defiant Disorder (ODD) an ongoing pattern of disobedient, hostile, and defiant behavior toward authority figures that goes beyond the bounds of normal childhood behavior. When a child cannot seem to control his anger or frustration, even over what seems to be trivial or simple to others, the child will often react in violent or negative ways to his own...

I don't know if you could go out for a few hours after husband gets home or have someone watch him. Where I live there is a crisis childcare where you can take your child there if you need. You are not failing. Being a parent is hard, especially if they have behavior problems.
I know the feelings of just wanting to disappear. What sometimes helps me is knowing that I can take care of my son better than most people can. I don't know if you are in therapy just for you it may help I don't know. You are doing great.
I bet you are a fantastic mom. Don't lose faith!