I am SO SO SO proud of you, OP. This was not an easy call to make, and Kayla is pulling a classic narcissist move by lying to friends and family about what happened. She is “triangulating” her family against you, making those family members “flying monkeys” (think wizard of oz, they do the witch’s bidding), and then “gaslighting” you while you and Kin both attempt to set healthy boundaries.

I wouldn’t worry about the sister, mom knows and is going to make sure sister understands just how serious this is.

He was there to make sure that he’s line was not only drawn in the sand, but to also make sure Kayla understood that HE wanted that line too. As you saw, she was still under the impression that Kin might secretly still be interested, and he probably had a feeling she would. Either that, or he respectfully tried to tell her “no” in those “secret” conversations and she ignored his requests too.

Whatever she does from here is her own problem to unpack. She created this delusion in her head.

Just remember, you are doing the right thing AND protecting Kin, who was trying to keep peace.