Dislikes Sister and an old friend

My wife has recently gone through some changes with her sister and an old friend. My wife was never close with her sister and this old friend growing up, but we've had a great relationship with both in the past 20+ years. A recent visit from her sister however sparked a memory of long ago when she didn't care for her sister. She really seems to dislike her now and I can't change her mind. My wife has accused her of wanting to move in with us and me falling in love with her. It's very frustrating and no manner of explanation has worked. I found myself getting angry and snapped at her a few times since she wouldn't let the conversation end. Same thing happened with an old friend. Disliking her now and accusing her of wanting to steal me from her.

My current idea of handling this is just to explain it to her sister and our friend and not to have further contact with them, which is unfortunate, but I don't see any other solution. The current confrontation about her sister was when I mentioned that she called and wanted to say hi. Her sister lives far away so it would have just been a phone conversation and not a visit.

Just wondering if anyone else has had this issue and what they proposed as a solution.