What would you do fr

I have a friend ， a really close friend imo, we’ve been friends since we were kids. However , her older sister’s husband has been asking me out and hitting on me etc. when I asked him like you know her sister is my friend he said he doesn’t care etc; so I told my close friend and I presume she told her big sister because I would do the same for my sister if someone told me about her husband. But now this older sister is trying to befriend me like make me her close friend too, I find it a little weird cause 1 we’re not the same age and 2 I have caught her several times deeply staring at me and I don’t know what to make of it. She thinks I’m evil or what?

What should I do? I have told the husband already that I’m not interested in him and I don’t want to break a happy home and to me it’s obvious he’s stepped out before but it’s the wife’s actions that give me questions. What would you do in this situation