Hi, whateverittakes! I just wanted to pop in an offer some support. Unfortunately, I don't have any sage advice for you, but I will say that I understand your pain and I know how difficult things are for you.
Honestly, no one can tell you whether you should continue to work on the M or if you should walk away - only you can know that, and if you don't know it now, don't fret. It will come to you.
I think all of us go through doubts, and everyone here questions whether his/her spouse is truly done with the marriage.
And we all ask ourselves if we should continue to hang on.
I'm sorry that you find yourself here, dealing with such a painful time in your life. Regardless of what happens, the pain will pass and life will get better - whether you're with your H or not.