bluerain (and Mark) ~ where you are sounds like a wonderful place to be, and I think you've found 'letting go'. Doesn't mean you no longer love your partner, just that you choose not to let his actions hurt you anymore.
Not having children gives you so much freedom in this situation, to think about what you really want and to realize how great you really are, certainly not second to some man-stealing bag of insecurities and justifications, as you said. I can't imagine what makes any of this okay in someone else's head.
Take your chance - fly! Your H may come back one day, but unless you have a crystal ball, you have no idea what's going to happen and the best you can do is live a life that makes sense to you.
Good luck with school - it's a blast returning to studying as an adult.
