I would recommend looking at the 7 stages of grief. The past few weeks have been really difficult, after a pretty good few months. However, I had contact with my stbxh and it shook me up. You will move through these stages in this journey and no one can predict the time it will take.
The OW is there as a 'band aid' or 'solution' to his unhappiness, but he doesn't know that and might never know that. She's going to be there for awhile. Mine's been with the OW for probably about a year now. You'll have to wait her out if you want to try and save your marriage and who knows how long that will be? It's your journey now and your life, what do you want to do? Focus on you, hang out with supportive friends, breathe, and take it one day at a time. Last summer I didn't think I was going to live and I've come so far, all of us on this board have. You'll make it, but it will be the hardest thing you ever do in your life.
Me 55 H 49 Married 21 years No kids bomb 5/09 filed 7/09 divorced and moving forward 5/10
