Believe it or not, your W may be doing you a small favor. It almost sounds like you have no choice but to GAL and detach. Interact only when it involves the kids. I have a similar situation, but she is still in the house and our constant interaction makes it very difficult to detach, likely making the process less effective and lengthier. Act as if it is over and there is a better that your W will at the very least become less combative. Keep doing the back and forth and the odds of that are slimmer. I almost wish my W would move out and give me more space to practice 180's and breathe.
T:22 M:17 Me: 44YO Her: 42YO 1 son 13YO BD 5/16/15 Her affair w/ OW 3/15-7/15 Her: ILYBNILWY
