Baby Steps to Learn to Let Go of Stress

Stress is something that we are all familiar with. But what do we do when it starts being too much to handle? How are we supposed to change our response to stress when it is so programmed, such automatic behavior that we're often not even aware that it is unproductive? I know that it is really easy to dig yourself a hole that seems impossible to leave.
My natural response to stress is definitely not productive. I am one that gets defensive and easily frustrated or agitated when I feel like there is a lot on my shoulders. This effectively isolates me from even the people that are there to help. There have been many times that I have showered my husband in thanks after one of these times. He is my major support and yet at the times that I feel overwhelmed I find myself snapping at him. He handles it with such grace, gently telling me that he does not deserve that kind of treatment without making me feel worse. Often that feeling of safety that goes along with being accepted even when I am not my best is enough to help me turn things around.
But the real question is how to stop these unhealthy responses in the first place. Not everyone is lucky enough to be married to a saint, and it is my opinion that our saints are the last people we want to burden with our problems. Talking about things before they reach this point can be very beneficial. Finding someone whom we can vent to and depend on is a great idea. Just remember that these relationships need to go both ways: if you want to lean on your friend make sure you're there to return the favor.
The more practice I have dealing with everyday life and the stresses that go along with it the easier it gets. The trick seems to be a proactive approach. All those tactics I constantly hear about in the news sound good: yoga, meditation, proper sleep, diet, exercise, etc. I put all these into practice as frequently as possible, and still it is not always easy. So I wonder if there is something I am missing? Is there something else I should be doing? Is there some other way to bring myself to that peaceful place that seems all too elusive?
I assume that everyone has their own personal version of this struggle, yet I still see it as a major personal failing. So not only do I work on dealing with the stress, but also I work on my reaction when I do not do as well as I'd hope. If allow it to eat at me, then it perpetuates the cycle. And this is something I wish to break free of; this is not going to swallow me.
As time goes by I grow closer and closer to that peaceful place I so dearly long to be. And I find that what I need most is to let go. I need to let go of this image of perfection I clutch so dearly, let go of the expectations I have for myself, allow myself to just be me and allow that to be enough. The more I put these beliefs into practice the less frequently I buckle under the pressures of daily life. It makes me wonder if maybe stress isn't even the problem. It definitely seems like my thought process is what is causing me all this trouble. If only changing my pattern of thinking was as simple as the yoga postures I attend to with such diligence, as simple as the breathing patterns I focus on during my meditations. If it were that simple to just accept myself and the life I have been given, my husband would have a much more pleasant life. Until then I have to just take baby steps.