I am glad you arrived back home safely. I am also glad you had a nice time away. You don't realize until you are away for a bit just how stressful life was/is.
I don't blame you for wanting to meet the parents of that kid. I think you were wise in stating that he could come over to your home. Leaving children at home, unsupervised, especially NYE isn't good. They can get into all sorts of stuff. Your s will just have to get over himself and one day, he'll be glad you insisted that he be at home where you knew he was safe and sound.
Your h has a lot of childhood issues bubbling up. The trip back east helped w/releasing some of that stuff...continue to list and validate (as you have been doing). I think that in the days ahead, you will hear more and more about his childhood. I think it did him a world of good to go back there and revisit the area.
Happy New Year to you and your family!
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.