I have no wisdom about h's, but one thing I have done with my boys that has helped my own worries over their response to this situation is to find an excellent counselor who specializes with working with (in my case) boys.
I insisted that they both go at least once. S1 went only once, and he decided he didn't need to go anymore (and the C agreed that S1 seemed fine), but S2 embraced having someone to talk to, and he went a number of times. Recently, S2 has felt he can do ok without that support, but in both cases, the counselor let the boys know that he would be willing to see them anytime they might need.
As I said, I think having someone who I trust knows something about kids dealing with separation and divorce - and both me and my h met with this person - confirm that the boys are coming through fine has helped me relax a bit. I know that all of the problems between H&me will impact the kids, and this counselling won't keep the impact from happening, but it helps the boys and me (and I assume my h) to know that there is someone other than me - who they feel protective of no matter what I do - to let their feelings out to. I think it also validates for them that sometimes we all need outside support to get through difficult times.
One thing the counselor pointed out to me the last time S2 went was that S2 could describe how I would get stressed out or upset, but that he also could identify that I was finding resources to let go of that stress or upset. In other words, even if I can't keep a brave face on all the time in front of them, the boys are seeing me find ways to deal with it and that helps them to not worry so much.
You might have already done all this; certainly even a trusted clergyperson could do the trick. I just thought I'd add what has helped me with the question of how to be around my kids.
