G, I'm sorry about all of this, but I would be very surprised if he showed up today. I know that it hurts your d very much that he's acting the way he is, but she will need to concentrate on her confirmation today, hard as it will be.
As for his family, what a bunch of crazy folks. Harboring grudges about something that you had nothing to do with. Laying blame on you when they should be looking in the mirror at themselves. Been through that w/my sister when her h died. His family pretty much acted and said the same things to her. As I told her and I will tell you...your h is a grown man and if he chooses not to stay in touch w/his family, that is on him. You had no control over that..he was not a possession or a pet that you could give commands to.
As for your h adopting your son, that was something that should have been between you and him. His family should never have been involved or offered up free lip service on the subject.
I still believe that your h wasn't going to return. They talk about coming home for some time and some of they never do. Your h is still searching for something within himself and he's got a lot of searching to do. Each time something happens, it will be another excuse not to return. He really does have a lot of issues to deal with and it's going to take him some time to figure things out, if ever.
Please keep your focus on your d and her special day. Make it as special as you can. Your d is going to need your focus, love and support today.
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.