I was there too a few months ago - when H and I separate last July I thought we would work things out within a few months. When it didn't happen, I came to this site and began the DB stuff, I saw it help me distant myself from the R. At times I felt worse and other times better this way. I think it is hard to let go when there is history, strong emotions, and children involved.
The letting go part is for yourself so that you can get your life back under your control. We may not be able to control the stitch but we can control our reactions. I think DB tech work period - it doesn't guarantee a spouse will return, only that you will have had better tools to work with. Either way, the tools help one to come out better than when they started.
I know if my H didn't return or it should suddenly not work out I will be ok. I didn't feel that way before starting here. I learned that you can't make a R work alone - the book says that one person can start the changes needed but it doesn't guarantee a result. The reason it works or doesn't work has to do with what the other person wants. We don't get to control that - just our responses to them. Hard thing to accept. But the support here is the only reason I am ok today.
