What I can't do is "cut my losses" like people say and move on. I can't let go of that future
I imagine what we could have together even though if it's anything like the past and present I'll probably die from the stress.
So not only do I have a hard time letting go of the future but it's also some stupid imagined future.
I don't want to turn in circles either so what's holding me back?
Since you're here, I presume he's got BPD traits? Well, one of those traits is a black or white perspective. Separation would be in a gray area he can't perceive, not quite married and not quite divorced either.
However, you - like so many of us - didn't want to 'give up'. You know the story, "Maybe the next recycle will finally work... ." Hope rests virtually eternal with us. Even if it now is only the wisps of dashed hopes and dreams.
Have you read about the 5 steps of grieving a relationship loss? We have a thread here on the boards describing that. The last step is Acceptance. You need to accept that it is Over. (It takes two to make a marriage a success, but only one to end it.)
Fine, you don't have to burn your bridges behind you, we don't want you to overreact that way anyway, but you do need to Accept the Reality.
While your head can accept that, it may take a while for your heart and sense of self to come to grips with that. That's just fine, you don't want to jump into a rebound relationship before you're ready. So... .give yourself time. Concentrate on yourself and your children, in time the new normal will feel... .normal.