I know how hard this is for you. Most all of us have gone through the same thing you are going through right now. I know its hard to believe that the Sandi's 37 rules might actually help you right now because they are counter intuitive. You heart is telling you to keep pursuing your S but, that is the exact thing that is pushing her farther away.
Sometimes we come on here and seem a little harsh about peoples situations. I think the VETS know that sometimes we need a smack upside the head to get our attention. I know I needed a couple. Its not meant to be cruel its to get your attention so you can accept what is actually happening. Our marriages are in grave danger, all of our marriages. That is why we are here.
Live your life that way with that understanding. It will make your 180's GAL and DBing more effective and easier. It will also help you heal your emotions faster too.
That is not to say give up on your efforts. Lovingly detach and act as if you are moving forward with your life regardless if your S does finalize the D or not. Either way, you have to move forward whether you are getting D or your marriage is reconciled.
I know this because I did the same thing. What I found is that when I LEARNED and LIVED by Sandi's 37 rules, something positive happened. I stopped pushing her farther away. Thats not to say she has become closer to getting back together with me. She is simply not moving farther away.
It seems you need to lower your expectations to zero. She is leaving you because of the person you are being right now. Thats not to say your a bad person. Just the opposite. You obviously love her very much.
Be that guy she fell in love with when you two were first dating. Be that guy, only better, even if you are just acting AsIf (see Sandi's 37 rules). It will get easier the more you do it.
So, if pursuing her is pushing her away (and it is), STOP pursuing her! Do the 180. Read Sandi's 37 rules everyday. Live those rules as closely as possible. Its the only chance you will have to get her back. She doesnt like how your acting right now so stop acting that way.
I know you are scared and lonely, we all are. You have to trust that DBing is you best chance to get her back but there is no gaurantee. REMEMBER- She is not going flip a switch and just love you again right now. She cant do that because of the strong feelings she is experiencing right now. It takes a long time. BE PATIENT!
Also, if you are DBing just to get her back, IT WONT WORK! She will see right through that. If we can see it, SHE definately can. Make all changes for YOU! For the rest of your life. Not for HER. You will be physically and emotionally better off which ever way your M goes. I know its hard because I still have a hard time with it. There is so much at stake here. Give the DBing and Sandi's 37 rules your best shot. That way, if she still decides to D, you know you did everything you could to stop the D. Stay Strong!
She is not trying to fix your M so stop worrying about what she is doing and start worrying about what youre doing. Stop doing things that push her away and start doing things that will halt her from withdrawing anymore.
Do you have a printed copy of Sandi's 37 rules. If not, you can find them in the Newcomers forum. Learn them and live them. They will help.
I hope this helps you in some way. I pray for you and everyone who finds themselves here. I pray that we will all find a satisfying resolution to our R.