Will poor me ever leave me in peace?

Today I had a moment of great unhappiness with my ex-husband. I was hoping that he was making the decision to go, as he said. But it turned out that he is only going away for a week. I filled my thoughts with his laughing face and some pretty girl. But really, whether that is true or not, he still manages to upset me.
My friends say that I must ignore him at all cost, as he is deliberately trying to upset me.
When we were married, I would ask him, why was it that he found being nasty so easy and nice, so difficult? Why can't I just let him go?

answer:
He has been the only man whom you have been with for over twenty years, clearly it is not easy to just adjust to such a big seperation.

Also remember that every time you interact with him, he interacts with you in the same engagement of wills.
He asked me to email him, then he didn't respond and when I spoke to him about it, he tells me that his lawyer shall contact me.
He's being a dick, basically.

Tonight I just decided that I really have to consciously let it go. Much like the control I wanted to have over my pregnancy, and many other things in my life. I have to let what I would like to see here, go.
I cannot seem to have any level of hope on this matter.
What I must do though, is to be very clear about what I must do for my daughter and I, and that is starting to happen.

I just have to walk on.