GG, I'm glad you called the xinlaws. You've got a lot to think about, but I'm glad you forgave your xh. He's carried a lot of guilt for a very long time and you know what, it's good that this happened. Your son can determine just how much contact he wants w/his father and you can step back from the situation. As for you, you have control over your situation and can also determine just how much contact you want w/them, not the other way around.
Now about your h, I do not think he visited w/anyone yesterday. If he did, I would be surprised. He's another one carrying a lot of guilt and shame for his behavior and the way he's feeling. At least the day is over and done w/and hopefully you can get things back to normal in a day or so.
I think I would tell him about the phone call. I certainly wouldn't keep any secrets from him. You did good GG!
Enjoy your day and try not to think too much about what transpired.
As for the strangest holiday experience...miracles do happen and God really does work in mysterious ways!
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.