i'm sorry your here, but your about to get a heavy dose of advice. First being buy a copy of divorce remedy!! Know that there is NOTHING you can do right now, but give her time and space. This is also a time that you need to start taking care of yourself, eating, sleeping (get some melatonin to help).
Try to pick up an old hobby, or start a new one. Get out for walks around the block, especially when your not feeling like it. Reconnect with old friends or get out of the house with your current ones. Its important that keep up with the kids, as they'll be aware things just aren't right. Do not bad mouth their mom, as those are paths you wont/don't want to have to explain later.
Follow sandi's 37 steps as best as you can, its gonna take some time to get them down.
Know that this is just starting and you have a LONG ways to go, a lot of work ahead of you, and that you are going to have your good days and bad days. And that's ok, its just part of the process. Read other people posts, don't be afraid to throw some support out there, cause you will get it back tenfold.
Keep making small posts till your off moderation, your posts wont show up immediately until then. Explain, if you can, why you think your wife shut down. What are some of the issues the marriage was having, and what you think you might have done different if you could go back in time. Cause those will be the focus of your 180's (the opposite of what you were doing). Be as brutally honest with yourself in your posts, cause you will get better advice if the vets have a better picture.