I am sure he already knows that she is rude and you can’t possibly enjoy her company. What do you plan on accomplishing? Is your goal to cut her off? If she is married to FIL you kind of can’t fully avoid her but basic minimum should suffice. I keep time with my SIL (brother’s sister) to a minimum. My brother is important to me so I can’t go no contact with her. My husband’s sister is also rude and so is her husband. Luckily she lives far and we don’t see her much

So she wants contact her when you contact her she doesn’t reply. Bizarre