Thank you so much for your replies everyone.

In this situation, there have been many moments where I’ve wanted to let go, but I was afraid to because I was scared I might miss my chance to keep my family intact if I let go and gave up too soon. At this point, I finally, truly do feel that I have done all I could.
You are all correct: my H has me locked in his mind as a solid plan B. He had asked me to call him last night to talk (once again, roping me in). I knew better this time and did not have expectations, though my hope rose slightly, and my curiosity was piqued. We talked for a while, and it was more of the same confusing, waffling, vague stuff from him. It became very clear that I’m Plan B. He talked about how this is “just a piece of paper” (??) and “nothing is going to change much” (???????) and he’s conflicted, etc etc etc. I honestly have no idea what the point of that talk was or why he wanted to have it.
Blu, I think you are right, about it all. I do not want to be plan b for anyone. And I do not want to hang on so tightly anymore. I have been terrified to let go. Terrified. For so many reasons. I’ve been afraid that it meant letting go of hope. I think I needed to feel like I had tried until the end. And I do feel that way. It is absolutely time to let go; I can say that with absolute certainty for the first time at this point. If my hope for R disappears as a result, then so be it. If hope can exist somewhere parallel to full acceptance and release of this situation, so be it. But it’s time.

I think my past attempts at letting go have been thwarted by my fear that I would somehow give H the wrong idea or give him fuel for his fire. Im ready to accept it if those are the results. When I think of him saying last night that nothing ls going to change with this divorce, I’m frustrated at myself that I didn’t correct him. He is wrong. I was honestly stunned to hear him saying that, and I regret not setting him straight. I’m contemplating whether I should, for my own piece of mind, find a time to communicate that directly.

For now though, I’m spending time confronting my fears and anxieties and sadness head on. I’m not done crying, I won’t pretend to be done being sad or sacred or anxious about this. But I’m focused on gentle acceptance. This is happening. This. Is. Happening. It is not in my hands and I can finally, actually accept that truth. It may not sound like much, but it’s a big step for me.