shaver, it is hard to let go, but the sooner you do, the better it gets. Holding on is only hurting you right now. She feels like she just can't be with you... its a feeling, you can't change that, so give her what she wants... set her free. The kids will have a tough time, but they will adjust. Just give them your full attention when you have them. Bury yourself in being a great dad. Focus on you... She only controls you if you allow her to.
How bad did you want to work on your marriage before your W bombed you? How bad do you want it now? Do you see how the fear of Loss causes feelings to change. Time to turn the tables?