I've actually held up the kids' ability to forgive as an example I am trying to follow - I've said that it is good that they have a positive relationship with their dad, and that I was hoping to continue growing and be able to "get along" better through forgiveness. It was actually a form of apology, since I reacted negatively recently upon seeing the gf with the kids and x during a drop-off - I said I am trying hard to stop that, that it is time to forgive and let it go, get past it. I didn't give him any response to his saying that his dad never asked him how he felt (my feeling is, that is a shame; not sure if my body language sent that idea). I think the whole thing came up when he mentioned the weirdness of the gf's kids coming over to our house.
IC today said that it is good to check in with the kids every now and then; that I would probably be doing this, anyway, opening a door that the kids might then jump on. But to let them know that I am open, considering how they are feeling, etc. It doesn't have to focus on the divorce - just life in general. And S and I have had those kinds of discussions, too (about school pressure, friends, girls). I just try to find a quiet time, one that he isn't just sitting across from me "in the hot seat," where I can ask a simple lead-in question and see if he has anything to say. If he doesn't, I tell him ok and that I am there for him whenever he'd like to talk about anything.
About the x's statements after the last session, she just said to make sure to address it with the next meeting, right at the beginning. That the anger and baiting is not surprising, since he was always most comfortable with me acting out / defending / being upset, etc. He didn't get that response this time.