Tough one. I guess we (meaning the "angry" folk) all had different things that set us straight, made us snap. For C4H and myself, it was the threat of losing the M. Sad it had to go that far. For my H, it was a new job and environment, less financial stress, etc.
Of course, it's a multi-step process. 1) There is an incident that makes you snap out of it 2) you look back at your behavior and feel like you were kidnapped by aliens 3) You act completely different, try to be aware of your actions on others, calmer.
Seems like your H is still on #1, on and off. He's feeling pretty low in the self-esteem department, that's what H and I felt when we were in "angry" phases.
Hmmm, let's listen to him. He said that he feels you don't need him. Yet, when you ask him to do things, he doesn't do it. How do you say it...seems that you're a calmer person and you only speak up when you've hit your stress level (you admitted to being in a mood and then letting him know how he never helps)...maybe this made him feel that he always gets you angry, lets you down and is a failure.
If you know he won't help, try to plan ahead of time how to ask him to do certain things instead of hoping, again and again, that he'll somehow magically know to help. Make a list together...thank him...tell him what a help he is, all that stuff. A little positive reinforcement goes a long way.
You know. My H has an employee that seems similar to your H. Very hot-headed, can't see the other perspective, gets really bent out of shape over things, intimidates and damages relationships with his attitude. H and I talked about it, and the main needs for him are: respect, being needed, being listened to, feeling powerful by being needed, respected and listened to.
I think H's self-esteem is damaged a LOT...he realizes that with his A and such, and your independence, he's lost a lot of credibility, validity, and respect.
Are these the same needs for your H? How can you start pushing those buttons on him to get him to behave? Let's get creative.