I would have been hopping mad at the longed for get together being totally ruined too.
You will have to make it blatantly clear that you want to have just the three of you, and no hangers on.
As others have pointed out, a really good friend will understand, and personally, it would have been better to have said so at the very beginning : head it off at the pass as it were.
Even good friends can be thoughtless, but a good friend would ask first, giving you a chance to refuse.
Which you didn't.....
This is in no way your fault, but you really have to make it clear that blubbing in front of their husbands would be unbearably embarrassing for you.
Good luck, and be firm!