hey, Bittles. Most of what we worry about doesn't even happen. So you can relax a bit. I am sad that your daughter will see again, what a jerk of a father she has, that makes me sad in my life, too, but she has an awesome mom...and like they say, as long as kids have ONE good parent....they're ok. (and yours sound more than ok!)
And anyway, this whole situation is not within your influence (whether he goes or not). Stay there, with what you can influence, and let the rest take care of itself. You can influence your own behavoir, and how you treat your children and other people...but beyond that you're just spinnin your wheels, out in the larger circle of concern, over which you have not a shred of control.
When I can pinpoint what it is exactly I am concerned about, and then hone in on what I really have influence over....I find that worrying and brooding is a choice....so I worry and brood

until I figure it out (yet again) that it's not doing any good, and then I drop it. Sure it's still out there, and I'm still concerned, but when I can't do a damn thing about it......what a waste of energy.
Last night I went to a performance at my daughter's school. I was a little nervous because I sure do hate seeing my ex, his wife, etc. (especially now that he is dragging me to court again next week).
My friend wanted to come with me, which surely helped bolster me, and from the second I walked in, I was besieged with friendly faces, parents and colleagues and the night went so well. My daughter was brilliant (of course) and I didn't even know my ex was even there, until he came to gather our daughter at the end (dad night).
So, last night was and example of things we worry about sometimes never happening....
So you can practice walking tall and ignoring him another time....or he shows up and you get to show off....either way, it's all good.....