That's a shame.

I am sorry you are going through this.
I really, really wish I could offer more than my well wishes, but there's so much in that that I don't see what I can offer to you.

At best, I would say that if I were you, I wouldn't worry about his wife not liking you. That's her loss, as I see it. You do what you need to do to be there for your son and grandchildren. Don't let her stop you from having a relationship with your son and grandchildren.
I really wish I could offer more than that.

Please know at the very least I am praying for you and your family.