Hi Blue,
I am following behind you with a middle schooler who has a bipolar dx. He has always had outbursts, but as he gets older these get worse. He goes to therapy every other week, which helps somewhat. I am the main focus of all of his anger. I constantly hear how much he hates me and wishes I was dead, etc. It's not all bad, though, sometimes I am the best mom in the world.
I agree, it is very tough to deal with when in a depression, or an angry hypomania. My t definitely helps me through these times.
Hopefully the residential treatment will help your son. At least there is some hope for relief for you an your sons.
Good luck,
Bluemountains