I really don’t know what to do and it’s making me so upset I would love your help. A close friend in our friendship group had an affair that lasted a year with some one that she was very close with. The affair ended , we all vowed not to say anything as their was a child involved. I did confront them both and her lover said he hoped the marriage would end and they would be together. Any eat fast forward a few years later we went away with the girls and low and behold she ends up sleeping with a stranger. I did tell a few people in our friendship group this but every one just turned a blind eye. Our relationship is now very false and strained , all my friends outside of this group think I should just walk away and not speak to her. What’s bought this to a head Is that my sister in law become estranged from us and become very unwell , I found out that she new this but never told us knowing that we were worried sick. I just don’t know how she can be so blasé about everything, she’s so sure that everybody is so scared to tell her husband that she’s totally arrogant about it I don’t know what to do. We have gotalot of mutual friends some know some don’t. I have started not going to things now when she’s there.