Hang on in there. You are awesome with your listening, accepting, validating.
I'm taking lessons from you!
This day with your H looks like a major step forward in terms of a good ongoing relationship.
He's seen that he can be with you and the girls and feel OK (well, probably feel great, but he wouldn't admit to that yet).
All that stuff about not wanting to give the kids the wrong impression is what my H goes on about all the time too. My view is that he's backed himself into a corner and is feeling even worse than when he was coming around to visit us.
Either way, all we can do is to focus on having nice times whether they join us or not, and keep validating what they express as their feelings. The rest is up to them.