Gal, please read Leah's thread. You and she have a lot in common. Lots of mood swinging between trying and throwing in the towel.
I'm not going to wade into the hope discussion again. People feel strongly about this. I will say that in general you have to let go of the idea of him coming back. Maybe think of it as a door, but perhaps one that is locked but not deadbolted. If you do retain your hope or whatever it is, you likely will continue to suffer.
My H rages at me and punishes me financially every single time I tell him something he does not want to hear. For e.g., D won't see him or the kids are hurting (or in S's case, hurting himself), or are having problems in school. I have learned to communicate with him in very bland language and to use the passive voice to avoid him believing that I am blaming him. The hysterical thing is that he will often call me passive aggressive for doing this, even though I'm doing so to avoid his monster.
It's actually good that he wants to talk on the phone. Far more personal than the texts or emails I never get anymore (though I truly have no desire to speak to mine). Find a picture of someone in your head that you are polite to, but distant, and think of that person when you deal with him (for me it is often an opposing counsel that I do not like).
As Gordie noted, until the path is clear, repeatable, and (I'm going to add) stated to third parties with no tears or sadness, stop the standing or going talk. Just live your life. Make your choices, deal with the logistics you have to face. Work through the sadness, the tears, mourn the future you envisioned and as much as you can dream about the one you could have for yourself focusing on the parts you control.
The rapid cycling you are experiencing is like standing in the ocean. The waves are fast and furious in the beginning, over time the amplitude lessons and the frequency of the next wave lengthens. It really does.
