I am sure that is very, very difficult and it is important to allow yourself to feel whatever it is you need to.
So, maybe while you feel what you need to feel we can maybe help you find some positives. You said yourself your H is a good dad so you know they will be safe and well cared for. It is good for you to get out for a night and know in the back of your mind your children will be okay. Those things are good, right?
We all have to grieve when certain things happen in the way we wish they didn't. While this is just my opinion I do think it is important to have hope but adjust it accordingly.
When it all comes at you so fast it is very difficult to keep up with ALL of it so just take care of you and your children and let H deal with his own stuff.
And just so I am "playing fair" I know I never really typed out ALL the particulars of my situation as I joined this site a bit further along in the process (IOW, it was 13 months after the bomb). If you ever want me to type it all out I will so you can see how many zillions of mistakes I made and you can ask me if I am nuts (hint: I am nuts!).
As I said, I don't have children but otherwise I can really relate to all other aspects of a separation. I did it ALL wrong for a LONG time. I know it's easy for me to say that now and maybe everybody just has to experience it but I guess that is one of the reasons I feel so passionate about all of *this*.
You will feel sad on Friday and that is okay. We will be here to cheer you on. What fun things will you be doing?