This is a photo on my (f28)Instagram. My brother in law (m42) reacted to it in DM, and said the above. I feel I replied normally, but now my sister (f39) apparently saw the message and is saying that I engaged in hot discussions with her man! I am myself married and I feel so bad now. I told my husband who said I did nothing wrong. Any idea how I could approach my sister ?
Yeah, it’s a total breach of trust towards both you and your sister, and you have every reason to be upset by it and to take your distance from him.
It’s fucked in many ways - that you’ve known each other since you were twelve, that he chooses to creep on his partners sister for some reason, that he chooses to send creepy texts to women behind her back, and that he is creeping people out by sending weird texts at all. There’s a lot to be upset about and little to tolerate here.
Your response is normal. We try to avoid conflict.
Your sister’s reaction is not so strange - he betrayed her and revealed himself as a total creep, but it’s a lot to process so it’s easier for her to pin it on you than to reevaluate her entire life. It’s a normal reaction and part of the psychology making abusive and unhealthy relationships possible.
My recommendation would be to not allow men to be passive bystanders to their creepy behaviour. He is the problem here, and your sister is going through something where it’s hard to think straight. Try to be patient with her. If this becomes primarily a conflict between you and your sister he has succeeded in replicating some extremely formalistic bullshit.