J.C.
FIrst of all, block them on Facebook. Your personal / family dirty laundry should not be aired on there for all to see. That's immature BS in my opinion.
Next, since you are obviouly dealing with immature people, make some adult rules for them to follow. Do this with your husband. If they don't follow the rules, then they can't come over. If they don't like it - fine. Let them absorb it and then make their move. They'll be angry at first, but once they realize that you are serious and not taking their BS anymore, they will back off a little.
Good luck!
You cannot let these people walk all over you guys - if they can, they will.