I agree with you John. Your wife left you, so why would you be there? So she could put on the front of having the happy family? Absolutely not anything in that for you. Let her face her family alone. They are a lot more likely to tell her she is making a mistake.
Good question. Was he invited? If not I would agree.
Don't bet on family for saying that she is making a mistake though. They have bias eventhough they have the best intentions at heart for both of them.