How to let go of resentment?

I am really struggling with resenting my DH. He got a great job a couple weeks ago (after being unemployed for more than two years) and promptly was fired for something, details are vague. This is the third job he's had in three years, he gets fired or laid off every time. When he's home, he putzes around the house and spends hours shopping online or creating rants for message forums. I have SO MUCH resentment built up towards him for the last 22 years of this; if it wasn't for me, we would be homeless. I am not ready to divorce, I want to make this relationship work, but he sees no problem with his behavior and refuses to get help or change. 

So once again, it has to begin with me. How do you let go of resentment and stop "feeding the beast"? I don't want to feel angry and bitter all the time, but it's so difficult.