EricT, Listen to Azzork the wise. He has helped me the last couple of days immensely. My wife is considering divorce after 26 years so I right there with you brother. I'm no wise man but I learned a few things these past few months.
You can't put her in a literal or figurative cage. There is is no leash. If she does not feel a bond to you, you got nothing.
Keep busy. I signed up for a community college continuing education night course for this fall 2 nights a week. Its still August and not to late if this appeals to you.
I go to a meditation class twice a week now. I find a lot of compassion there. I love the whole thing.
My kids are older then yours, I would love to be able to spend time again with them when they were little. Enjoy them, be their rock, their Dad. That's powerful stuff. You said your wife was crying over them. Be the most important consistent stable thing in their life. Give all your love for your wife to her children. You will never be sorry you made this choice.
Till now I have been reacting to my situation just like you. I have finally seen that I am stuck thinking about the past in relation to the present. It has only pushed my wife farther away. I now am trying to stay in the present moment and think about where I want to be in the future. It has been difficult to manage the emotions, they seem to get in the way. But if you keep trying it seems easier. Breathe in, breathe out, repeat.