u/vanya_vex

I (27F) have a close friend, we’ll call her S (27F), we’ve supported each other through a lot over the years. She’s genuinely one of my closest friends and I love her dearly, which is why this whole situation hurts so much.
For context, I’m very against cheating. I’ve been cheated on before and I don’t tolerate it. No second chances, no excuses. S is more forgiving because she stayed with a guy who cheated on her multiple times and I saw firsthand how badly it destroyed her mentally and emotionally. I spent months supporting her, listening to her cry, helping her rebuild her confidence, and reminding her she deserved better. Eventually she realized it too and left him.
Recently she started seeing a new guy and finally opened up about him. According to her he’s perfect, loving, attentive, basically “Prince Charming.” Naturally I was excited for her and asked when I’d get to meet him.
That’s when her whole demeanor changed. She told me I needed to “keep an open mind” because he’s married, but supposedly “getting divorced.” When I asked if he had actually filed for divorce, moved out, separated, literally anything concrete, she admitted she didn’t know. She then showed me his social media and started insulting his wife, saying she isn’t nearly as pretty as her and that she makes his life miserable. So now I know the wife’s name too.
I told her I couldn’t support what she was doing because it’s wrong, but ultimately it’s her life and her choice. I ended the conversation because honestly I was angry and uncomfortable to continue.
A few days later she asked to meet because she was upset with ME for judging her. She told me I don’t understand “true love,” that I’m too rigid in relationships, and that I cut people off too easily instead of giving them second chances.
Then she started trash talking the wife again and comparing me to her because apparently having boundaries makes us both “controlling.” That’s when I snapped and said maybe I should contact the wife myself and ask for her side of the story.
S immediately started crying and begged me not to. She said I would ruin her life, that he told her they need to keep the relationship secret “for now,” and that if his wife found out it would upset him and destroy everything.
I told her that sounded like obvious manipulation and reminded her how devastated she was when she got cheated on. I asked her how she could knowingly do that to another woman after experiencing that pain herself. The conversation ended with me leaving again since there was no reasoning with her.
Now I feel conflicted. Part of me thinks it’s none of my business, but another part feels guilty knowing this woman probably has no idea her husband is cheating on her
AITA for threatening my friend I’d tell the wife?
And WIBTA if I actually did it?