Well this is an inside job - not external. This might require some self-coaching. Although... how is he about being fair minded when he is upset? I ask because with some people you might be able to decompress the situation AND save yourself the guilt just by asking him during one of those episodes, "I'm feeling sad and guilty because your upset. Do you believe that I have fault in this or can I just feel sad that you're not happy?"

Some people are irrational when they are upset, though some people will snap back to reality with such a comment. You are honestly sharing your feelings with him, sharing that you are feeling empathy for him, letting him know that his unhappiness is a source of sadness for you, and that you are willing to take responsibility for any action that you might have taken to contribute. Many men have a protective instinct toward their wives and confronted with the idea that his outburst is having negative effects on her (I know it should be obvious but actually saying the words can make a profoound difference), many pull back and get a grip, or at least assure her that it is not her fault.

If he is too far gone emotionally, it probably won't work immediately, but you might find him coming around later and apologizing in cases where he never would before.