Depression has set in.

[cat03]

the fist few months are the worst, but you can make it. I cried when my kids where not around, to a friend, to a cousin who went through the same thing, so I didn't have to cry in front of my kids (though you can't fool kids it helps for them not to see their mom sad) I know you feel this is the end but it isn't.
After the 2-3mth or so, it finally dawned on me that I could make it alone if he never came back. I know it is something you rather not even think about, but trust me, it is the ONLY way to regain some sanity and peace. To know that you do not need him to live, that you can be happy without him. I know it hurts and it is the last thought you want, but once you find it in your heart you will have the peace to ride out this storm, I promise. Do continue with IC, when he takes the kids go out and find new things to do, the ol' GAL, work out, join a book club, anything, dont' stay home alone.
Your d12 is too young to be your crying shoulder, I do agree that it is not ok to hide all feelings, it is your job to make them feel secure as you are the only responsible parent they have at the time.

Any changes you do on yourself, do them for YOU first and foremost. Always remember, you can't control anything, you can't control his desicions, the only thing you have to try to control is your thoughts. I highly recommend you read "eat, pray & love", it will help you lots.
Over all, pray, that's what saved me, that's the only way I got to have any peace, to be able to wake up without crying, even if your prayer, much like mine years ago, is "I'm hurting, please help me". I have found peace, we are D now but I found myself, I found God for real and I am happy and love my life. You will be ok, but you must believe it first.