You need to stop talking with her about your marriage.

It is in the book.

Don't make wise cracks to her, don't argue with her, NOTHING.

She's TRYING to make YOU as miserable as HER. Don't let her.

"none of your business" is not a mature response to "why are you doing ..."

Try "nothing destructive to our relationship, I promise you I will always act in a way that will strengthen us".

I am going to re read these to collect the points up.