I feel for you, my husband gets like this, but not all the time and not every day. He, however, got on anti-depressants, what made him really notice how he was acting was when I would point out how his mood effected our kids (at that time they were 3 and 1 -- total barometers of others feelings)
This may sound crude, but try not to talk to him so much during the day, use the excuse you were in the shower, get out of the house and have not signal, etc. My experience is that you can't help him change unless he wants to change, what you can do is take care of yourself, if his mood is rubbing off on you, put yourself in a situation where you are effected less or encounter it less.
And also try to just tell him, "you are in a rotten mood, and you are going to make me in one, and I don't have time to be depressed today, so I am done talking to you for now." I used to do that to my husband all the time, it would make him mad, but I was happier, and he usually calmed down and came to his senses by the time we talked again.