Nc for this as some details potentially outing. I have a friend, one of my best friends who I've been close to for over a decade. She's never in all that time given me reason to doubt her and has been really supportive and reliable and loyal. She's not bitchy or a gossip and would come to me directly if we have a problem so we can resolve it.
She had a very close friend who ghosted her over a year ago with no explanation and she was incredibly hurt by that. I didn't know her friend well but figured something must be wrong as it seemed out of character from what I knew of their friendship. Anyway, my friend got angry with her ex friend and then processed to tell me all the horrible and nasty, judgemental things this ex friend has said about me and our other mutual friends in the past. I was pretty shocked given that I've only met her 3 times in group settings and I was polite and made an effort each time so she really knows very little about me. I knew she was very direct and I knew she could be a bit mean but I saw no reason for her to be nasty about me given that we barely knew each other. I didn't really think too much on it given that the friendship had ended and I was disgusted at the things my friend told me she had said to her as well. Things like when she bought a new home she was surprised she could afford it, when they redecorated that she thought it was ugly and criticising her parenting when she was a very new parent and slags off other people who share my friends religious beliefs to her. I told my friend she was better off without and we moved on.
I've just found out that she's been back in touch with her ex friend for a few months now (never mentioned a word about it, which I'm assuming is because she knew she'd told me too much about her past comments) and she's now invited her to an event I'll also be attending in a fortnight. She's seen this friend more in the last few months than she's seen me despite me suggesting meeting up. (I'd assumed she was just busy with work and we'd been texting every few days as normal).
I now feel really weird about this. I wouldn't let anyone say horrible things about someone I cared about to me. To be honest I wouldn't tolerate the things she said, being said about anyone because it goes against my core values. But it's now given me a red flag for my friendship because how can she be friends with someone who's been so horrible about me behind my back? It also raises the question why this person felt they could say horrible things about me and her other friends to her in the first place.
They've been friend's since school so a really really long time and I get that maybe it's a sense of obligation to a really old friendship and I don't want to get into a childish thing of I don't like X so you can't like X either. I also suspect this other friend is jealous and a bit controlling. But am I unreasonable to now doubt my friend, her values and how much she has my back when she's with this friend? I feel like I want to address it with her but I'm not even sure how to go about it. I also have no interest in making any effort with her at this event coming up but it's a tiny get together so it would be really obvious if I don't make my normal effort. What would others do?