You will never understand where he is coming from so stop trying to. You will only keep hurting yourself and spinning out of control like you said. He is living in his own reality and in that you and the kids really have no part.
Have you considered IC or a support group? I have found both amazing comforting and, well, therapeutic. He is on his own in this and so you must be also. Take this time to grow for yourself and your kids. Spend as much time as possible doing small things for yourself (and I do mean for YOURSELF - not you and the kids.) You need time away from them in order to get yourself straightened out. Don't feel guilty about that. I know they are young but a strong, healthy, stable mom is much more important in the long run than losing a little time with them.
What are your hobbies? What do you like to do outside of your family and marriage? If you don't know, find out! Make sure that you do at least one thing each week where you can be around other people who share your interest. Join a civic group, a club, a bible study - anything you can to give yourself time.
I don't know how spiritual you are, but I can honestly say that this crisis has brought me to God in a way I never imagined in my life. I've been a Christian all my life but had fallen away for a long time. I'm now back in His arms and He has brought me joy and peace. Prayer is an amazing comfort to a wounded soul.
Know that we are all here for you. Keep posting and let us know what is going on. (((((KPK))))))
T19 M15 S19 XH47 M43 bomb12/4/07 PA5/07 S12/26/07 D final 11/17/08 Back together with no defined R 05/2010 confused....to say the least!!!