In spite of the anger and resentment, you've got to drop your psychological work elsewhere. Your kids don't have any skills for dealing with your sadness or anger, and your ex has got better things to do.
I have a bit of a mood problem. It seems that when my life gets really tough (bounced checks, trouble at work, arguments at home) I sometimes collapse into a depression. It's not often, but when it happens it surprises everyone around me with the change in my energy, demeanor, and general outlook on life.
The first time my current sweetheart crossed my path I was in no mood or frame of mind for anything beyond my own sad story. When we crossed paths the second time, she was well prepared with my trigger words and actions. And I was broadcasting on all channels my desire for a partner to step up and be enveloped in my madness.
I wanted my marriage to continue, but it did not. And that failure has given way to such joy and happiness that it's hard not to thank my ex-wife for giving me this new opportunity for a joyous life.
I still want to get in better shape. I want my health to be an advantage in my older days. I want my kids to look up to me, and know that they are still several years from being able to beat me on the tennis court, or sprinting across any random field we come upon. I want my kids, but mainly myself, to be proud of me.
And I can still recall twice in my life, the thrill of that moment when I realized my heart was spinning out of control and there was nothing I'd rather do than be with this other beautiful person. Whew! Only twice? Dang, that's inspiration enough.
Get right with yourself before moving on to partner with another person. You'll be much more attractive to other healthy people, and better equipped to see and avoid negative relationships.
I'm almost always hopeful and joyous about this new journey. As a single dad, I have more time and more complications than when I was married. And if we can find the balance of these three traits between us, perhaps we can build "what's next" together.