I too live with a depressed husband. Check out the book Depression Fallout. This book helped me to better understand his actions towards me and himself and give me insights as to how I should react to his actions. I am now reading for a second time in two months to reassre myself that I am not losing my mind.
This is a terrible disease and when it has it's strongest hold the ones who suffer the most are the significant others. Only you can decide based on his willingness to get help and willingness to stay on that course and remaining aware on his own of his mood changes whether or not this is a storm you can weather.
It is very very tough. Hang in there and put yourself first and foremost!! Remember that nothing you can do is making this better or worse, it is all the disease.
You have picked an awesome forum to join full of people who understand and are there to lean on when needed.
Take care and keep us posted..........Jenn