Oh dear, I can see why that would be so hard. It must also mess with your head.
It sounds like you already know that what is happening is not ideal because you have identified that it's all on her terms.
I wonder if she is playing you, and using you, because she knows you still love her, and is maybe using that vulnerability against you.
As I see it, if she was interested, and genuinely cared, then she would want to hear from you too, and it wouldn't just all be in her control. It sounds very toxic and actually like it is a very harmful relationship for you. It sounds like she makes you feel worthless and bad about yourself because of what she says when you call, but also how often she calls and then doesn't call.
I wonder if maybe cutting contact completely for a while might be a positive step? I say that because it would allow you to get out of this vicious cycle of her being in control. She is effectively controlling your moods and how your week is, by when she contacts you. Maybe cutting contact might help you take back the control and get your life together a bit more, so that you can then decide if you want to talk to her.
It can be REALLY hard when you love someone to actually see, or face up to, what's happening, and so I really do feel for you.
Let me ask you this though, if she really loved you, would she treat you so badly? Would you treat someone you loved in this way? If not, what would you do differently, and why do you think that's not happening here?