Ladies, how would you react if your husband's sister indirectly kept trying to show you that "siblings love" is greater than "spouse love"?

Just keep ignoring

This is a never ending problem of every society.

All matters is what your husband thinks of you.
As you said your husband gives you priority over her so just stay happy with your husband.

It is a kind of a stinky problem where a good and loyal man has to pay more than a woman does because he is actually working hard or say, struggling to balance the relationships.

"So, when he fucks you, does he do that thing that I really find annoying when we have sex? Or is it just me?"

She's gotta go. You don't have to be rude but then again some don't get it unless they are speed in the face with it. She is trying to drive you away, she's if undermining you maybe not effectively yet. She is trying to get between you two run you off and have it her way. Don't listen to her shit. Your husband loves you more. If he gives into her run them both of and report the incest. It's probably against the law there too.

Talk about how great the two of you are in bed together.

I don't pay attention to their family

Ignore. You cannot compare and quantify how great a love is.