Sorry you are here. The keys to successful DB'ing are to detach, 180 and GAL. You must do these things and you must do them for YOU, not for the benefit of your W. Despite what she is telling you (that she wants you to fight for her), pursuing her at this point will only drive her away. If she's telling you that she wants to divorce or separate, she is done. She has already checked out. The way you save your M at this point is by detaching, 180 and GAL. Get the book and read it. Follow the rules. Read Sandi's 37 rules. Nothing you can do at this point will "bring her back." She has to want to come back on her own. Show her what she will be missing. Become awesome to your core. Become the best Dad you have ever been. If she's vacillating between talking about separation but at the same time wanting you to fight for her, that means she is VERY conflicted. That is a good thing. All hope is not lost. Detach, 180 and GAL. That is how you save your M.
Me: 48 y/o W: 47 y/o Together: > 20 yrs BD: Dec '15, then S 2nd BD: Mar '16, then I filed for D April '16: started piecing