S, Dbing is not just about saving your marriage; it is about saving yourself. Work on you and what you want to accomplish w/your life. You and your h were two separate individuals prior to marriage and during this time, you become two separate individuals. Dig deep, think about how you were when you two met...are there changes you can make to improve upon yourself, interests, etc.? This is a time for your to explore the world and find out more about yourself. This is a time that will test you to the fullest and believe it or not, you are going to discover a whole new you in the process.
At this time, you need to leave him out there. Allow him to spread his wings and fly a bit from the gilded cage. He thinks the grass is greener on the other side. How will he know whether it is or not if you do not let him go and find out for himself. Yes, you love him, but for now, you must put your faith and trust in God and allow him to guide him. Let him go!
I don't believe for one minute that two of you were so out of sync for so many years. If that were the case, your marriage would have ended a long, long time ago. You, the rational one, know exactly what you had up until a while ago. Cherish those happy memories for they will get you through the rough patches.
Again, keep the focus on you and your children. It's time to drop the rope and allow him to fly from home for a while. He really does need to find himself and discover that life isn't always the way you planned it. Looks can be deceiving and the grass is not always greener on the other side. Happiness comes from within and he must learn this lesson as he flies to other parts of the world.
You, too, have a new world to discover and it's time for you to spread your wings for a while as well. It may not have been what you wanted or planned, but for now, you need to find that inner strength to carry you through the days ahead and know that no matter what transpires, you are going to survive and be okay.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.