I only read your first post and none of the responses yet.....
Been there, done that!!!! We planned our trip, in-laws decided that when I told them we were going that meant I asked them to go also!!!! WHAT??? I never asked them to go.
Anyways, they asked me to book their trip, I have them my TAs number, then I called her FAST and explained that she was not to tell them where we were staying and please book them at another resort, I even suggested WL because they usually camp so they may enjoy. All along hoping that they wouldn't book because it cost so much more then they are used to paying.
They booked, they went..... First day at MK they called asked where we were so we met up with them in front of the castle they wanted to go to space mountain but we were headed to splashelse.....that was the last of them for the trip. They didn't even try to see their granddaughter ON her birthday IN Disney!!!!!
Really--were you surprised? I think you made your point about their intrusion into your trip. I think they were making a point as well. Sometimes you have to suck up a bad situation and make the best of it. It wouldn't have been worth it to me to be right to go the entire trip with out making contact. And I am a little surprised your husband let it get to that point. You didn't have to be joined at the hip and you might have been surprised that the situation wasn't all that bad. How was that relationship after everyone got home?
So I say go ahead and plan your trip, book your stuff but don't tell them where you are staying, just tell them you will decide closer in, name a few resorts you are thinking of but don't give it away that you KNOW where yet, if they ask, tell them your daily plans then go about it. It is easy to ignore your cell at Disney. Or have a meal with them, then do your own thing. You do not have to be with them during your stay.