[mrsred]

You didn't say if you are a stay at home mom, or if he goes to preschool or anything. Staying home all day long, week after week wih a child that is raging frequently. If the two of you are home all day together, speak with your placement worker about getting him into preschool a few days a week, preferably a preschool geared toward kids with special needs. In our area there is a program called Childd Find, where they screen preschoolers to identify areas where early intervention can help. Sounds like he could use some of that. But mostly you need to take a break from each other.
Another tip - you said you felt you were "called" to do this. Time to rely more on the "Caller". When I find I cannot take another moment I go into my closet and argue with ... oops, I mean pray to Him. It is only when I get to the point where I totally surrender that He can help.