As you are prepare mentally, I would let your W make her decision. I know it is unfair to you to leave you without telling you her intention. My W did the same. But she can't take the kids as they are old enough to make their own decision, who they wantto live with. Of course our kids are more comfortable to live with me.
I understand how you feel right now. My W left for just 9 hours. It was like hell. Especially for my S. We are all here to support you. Get a good L. Get good legal advice. You don't need to use the L if not necessary. But you know where you stand. Be prepare to use LRT. I hope that your W is not making a decision that she will regret.
