Hi E
Sorry you have to deal with this. I went through a long stretch of having nightmares (had them before separation too, always shortly before relapse happening). Mine involved my child getting injured while in care of ex. Or lost. Nothing worse than that.
Then, about 4 months into separation I started having dreams of good times, and woke up, and ended up crying because ex was not next to me.
I agree that NC is not avoiding feelings, and modified version of it helped me (I asked to communicate via e-mail, which is another issue, because he is such a great writer).
I do miss partnership, laughs, watching movies together, but when he offered to maintain friendship to preserve those things - I said I am not there yet (probably will never be).
The most helpful thing was a list of reasons I am divorcing him. When I start getting "touchy feely", I pull out the list and read it. Plus, he continues to behave in extremely self-absorbed way when it comes to visits with son - so this behaviour helps in a way not to pine over him,
The hardest part was 4 months after separation. Divorce is now final and it feels better.