Apparently from her e-mail, she's upset about her son getting his gf pregnant and turned to you for comfort.
You can be angry, it's okay. You HAVE been through a lot with this woman, and yet, you are still on a divorce busting site and not in the surviving the big D section, so I presumed that you were still interested in restoring your marriage. Considering all that has happened, no one would argue that you haven't tried and that the right thing may be to move on and never look back. I'm trying to figure out whether I should be writing advice geared towards restoring your marriage or not. I agree with the Gucci approach towards getting them looking your way again, but after your spouse is asking to come back, the rules have to change and an effort made to let your spouse back in. But that applies to if you are still wanting a marriage. If you don't, then you don't have to do anything you don't want to.
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer