Please help me stop becoming bitter & jaded!?

Once upon a time I was bubbliy and happy. Then I got married and then after 3 years he fell out of love with me a; then I had a 10 year on and off romance. Then I met "Mr. Right" dated for 3 years got married, now married for over 4. We've had our normal relationship problems and we've gone to counseling. i've NEVER caught him cheating but have caught him in a multitude of lies. Twice in the past year he has told me that he may want to be single again. He's never been married or in a longterm relationship...so he says that he doesn't want to take the "easy way out" and make the marriage work. I have to tell you; it's very difficult for me to not turn cynical and bitter and jaded. I can feel it coming on and I don't want to give in to it - I know it's self destructive. It's easy to say "Just Stop" but I need some tools. Anyone have any suggestions?