Your not in alone. In an age of entitlement there are a bunch of peoples relationship partners who are leaving in attempts to be "free", when they were "free" all the long, just married. They'll drop you like a bad dream.
What you need to do for yourself is to read the 'robx' postings. You need to take care of your physical and mental health first and foremost. Formulate a plan for yourself without your wife in it. Part of my plan would be gaining "single appeal", and taking care of my physical health. Improve your diet, cut down or eliminate alcohol. Its not your friend, especially in a situation like this.
GET BUSY, do things you like outside the house. Have fun, do some things for yourself that you have been putting off.
Keep checking here, because I'm sure others have something to add.