As far as I know from experience in therapy and living with a BIL whom I think is also depressed.All you can do is make him aware of how it affects you and encourage him to see a dr. But you may want to try Family Therapy; if its affecting you that much.Good Luck and let us know.Maybe someone else can give you a better suggestion or help.Then again what I suggested may be the key...
*hugs*
lynnie