Immature meta...sad, annoyed, frustrated.

I (52F) just need to vent. My partner (40M) has two other relationships. One meta (40F) is a joy and a delight, and we get along great. We socialize, she works for me on various jobs, and we hang out as a group with her other partner all the time.

My other Meta (40F) is, unfortunately, someone I was aware of before my partner encountered her, and is a walking ball of immature drama-generating craziness. She has been involved in other poly relationships that have had major issues with STIs because of carelessness with sexual health, and has a tendency toward demonizing others involved in her pairings. I was extremely hesitant when my partner said that he was interested in dating her, and expressed my misgivings as soon as I knew anything was happening--but I have no right to dictate who he chooses to love, and, to her credit, she brings things to their relationship that are important to him. My response was to limit my contact with her, not hang out with them together, and let him know that since we were fluid-bonded, I expected him to be careful, and if they progressed to sexual relations, we wouldn't be fluid-bonded any more, as I couldn't trust her to be careful.

They've been dating for about a year. Over that time, she made a few attempts to make me the "bad actor" for "limiting his time with her" (I have no control over his schedule, other than two regular date nights a week). Recently it seemed that we had settled in to a schedule/time thing that worked for all of us, and although I still wasn't happy about her presence in my extended intimate network, I was focusing on recognizing my partner's happiness with the relationship.

Cut to this weekend, when I get a call from a mutual friend, letting me know that this woman was involved in a relatively major trash-talking session about me at a public event, (a session the Meta reported to my partner as someone else trashing me, and her choosing to exit the conversation). In this gossip-fest, she revealed private information about me to other people, and generally went on about how I was "keeping her from the love of her life"....).

sigh....Some slight digging on my part chatting with a few other friends who hang out in the same groups revealed even MORE times that she's been running about, saying decidedly unpleasant things and spreading crap about me.

I am in my 50s, fer crissake...not high school. And I am more than a little annoyed that this woman, while professing to our partner that she's fine with their level of committment, accepts the amount of time he can share with her, and that she's perfectly happy with things...runs around to other people, proclaiming exactly the opposite and blaming me for all her unhappiness. Loudly. At great length.

I had to sit with my partner this weekend and tell him about all this. It sucks in a major way to have to tell someone you love that someone else they love is actively lying to them, and publicly sharing information that was entrusted to them as private.

I'm NOT going to put up with this...and I have no issue with taking her to coffee and clearing the air...but the problem is, her usual response is to then turn around and tell all her friends that "the big bad other woman is being MEAN to her"...so ultimately it solves nothing.

I was clear with my partner that since this woman can't be honest with her feelings and goes and spews shit all over the place, that even the most casual thing about my life is not to be shared with her.

I have done my best to be welcoming to the relationship, and have "begged off" hanging out (which isn't hard to do, as I'm usually insanely busy running my business)..but FFS, it would help if she'd grow the hell up.

I feel trapped by this woman's crazy. Our mutual partner is a wonderful man, and he loves her, but her insecurity comes out in such a destructive way. I'm the "evil" so even trying to talk to her to make it clear that I don't have any control (nor would I attempt) to end their relationship is met with disbelief.

All I can do is make sure my partner knows that he's not to tell her anything about my life, and continue to put up with the trash-talking. Gah.

Ultimately it's my partner's issue to solve, as it's about THEM and THEIR relationship--but the constant deflection she engages in is....exhausting.

I don't see an easy solution..so I'm just ranting. Thank you for the space.

TL:DR: Meta busily trash talking me and lying to our mutual partner because of her insecurities, and I'm tired of being the focus of her ire when it's not my issue.