Expectations, even bad ones can blindside you. I do understand what you mean about "worst case scenario", but that can bite you as hard as positive expectaions. I have the teeth marks on my butt to prove it.
All the healing we need to do takes time. So much time it seems. IMO it's important to take whatever times you need. I have lists of goals, from daily to monthly to 15 years out. May seem a bit compulsive, but it gives me something to focus on that has a positive outcome for me. It also give me something to focus on besides H and all that goes with that.
You're right it's just a setback. You'll dust yourself off and get back in the saddle (so to speak). There really isn't another choice.
I still struggle with the friend thing. He may not feel worthy to be your friend. That's a hard row to hoe. If he isn't behaving as a friend even some of the time (ie: sharing anything personal) then perhaps you can be there when there's difficulty with the kids. I've found that I ca reach out to my H easier through my D'. Just a thought.
