Depression can be a cruel mistress.
The one thing I don't understand, however, is the fact he did it while his wife pleaded with him from the other side of the door. I just can't grasp that he would put her through that situation.
Back in high school I suffered from heavy depression and considered ending my life more then once, but each time I did I always imagined my father walking into my silent, empty room, knowing I was gone, and busting into tears. That image stopped me cold every time, and it was just a fantasy. I could never put any of my family through the actual event right next to me.
Part of me is angry at him for that, but the whole thing is a tragedy none the less.