Okay I'll say straight up I should have stayed out of this in the first place and I'm heavily regretting getting involved in this way, but I'll try and sum the situation up as accurately as I can.

I have two friends who also have BPD. I'll call one K, and the other B.

Now, I met B a good few months ago, developed a massive crush on them, then that fizzled out over time to just really liking them as a person. However, things changed when K came into the equation.

B is in a poly relationship with quite a few people, but K seems to be somebody they're dating outside the polycule. K loves B, really really deeply and I can just see it, but they've been extremely insecure recently because B has been going around sleeping with people they dislike, ignoring their messages, and has recently started a sexual relationship with somebody whose kinks she finds incredibly triggering. 

Now, I've developed some protective feelings towards K. And while B has been out fucking others, getting fucked up etc, K has been incredibly incredibly distressed. I've been talking to her and trying to support her as best I can, and the more she's talked about B's behaviour, as much as I like B, the more I've began to split on them. Long story short, I've been encouraging K to break up with B. Which not only makes me feel like a two faced, shitty friend, but like perhaps maybe K is going to get the idea I have some sort of ulterior motive of dating her instead which isn't the case at all. 

Now, K opened up to me about alot of things. About how she feels unloved, unwanted, unappreciated, and like it's incredibly unfair that B can sleep with whoever they like and call it "poly" while when she does the same, B gets incredibly jealous and insecure. I see this as extremely unfair. But the thing is now I've thrown myself into this and if B gets wind of the fact I've been saying these things to K, I'm not sure how they'll react and honestly I'm scared as fuck, of losing both friends, or being seen as some asshole just trying to win K over when I'm literally just trying to be a good friend to K. 

I'm anxious, I'm scared, I'm worried and it feels like theres a huge knot in my stomach just thinking about all this. I'm questioning why I've done this in the first place, why I threw myself in there to begin with and why I didn't just be like "oh sorry you guys aren't doing well" instead of literally saying "B is acting like a prick and you don't deserve it that/they're toxic." 

This whole thing is a mess and I'm not sure if I'm overthinking or if I've literally been the asshole in this situation and poured jet fuel on a flame, if you will. I need some serious advice on this. What the fuck do I do, especially if K splits on me for some reason and tells B I've been trying to seperate them or something. I just don't know what to do, I just wanted to be nice but I think I've potentially made things worse.

I genuinely like B and K. I just think B isn't being the best tey can be to K. Now I'm worried I'll lose both friends and they'll spread shit about me being some fucking drama stirrer or something.