I really don't understand why she keeps reaching out to you like this. She can't be that socially unaware. I guess she can, but wtf. Why would she invite you to this? (I know you know how I meant that. (heart) )
Also, I'm irrationally sad that she's marrying your friend. I mean, you guys will probably lose a friend over this craziness. Tragic.
I bet a billion dollars that if you went you would find yourself in a very small gathering of her female relatives, two or three work acquaintances and one actual friend, who would be equally irritating/clueless. I almost want you to take a bullet and go, but I also like you and wouldn't wish that on my worst enemy.
The answer here is to give a pair of crotchless panties to your husband to give to her husband to give to her to be opened at the shower. That way everyone connecting you to this girl can see how ridiculous this game is.