I'm glad writing helped you vent. I'm sorry you are upset.
FOR BOTH OF YOU:
I really don't know what's going on or what I'm meant to do. We're meeting up with her tomorrow. My boyfriend is a mess because he feels like she's being duplicitous but also still cares about her. He also dislikes that she has said those things about me, so he doesn't know what to do.
Could not hang with people you think are duplicitous and cause you emotional pain and confusion.
He could allow himself to carry on with the process of detachment already in progress. She broke up with him. There's some "farewell kiss" thing. AND there's a scene neither of you enjoyed at the club with her and her friend(s). Why bother going out to meet with her tomorrow to get some more
crazy town? Wasn't that enough?
Could cancel meeting, let the "farewell kiss" BE farewell. Let her breaking up with him STAY broken up. Could just let it be so and skip the next installment of drama-lama.
You requesting things from your BF so you can deal with his other dating life is between you and him. If he's willing to meet your reasonable requests, fine.
I do not know how he expressed the need to meet agreements with you to the GF. In future, you could ask him to keep it simpler and not TMI if he went TMI and that helped fan this hooha.
You could ask him to make his dates with her and not bring up (you+ bf) agreements up in calendar scheduling with her other than simple "Nope, can't have a date that night. I have other plans." or "Sure, but then I have to be home by ____."
Could ask him not overshare details with his dating potentials. He doesn't have to explain WHY. If she presses, "I have other agreements to keep with my other sweetie" should suffice. They are dating, and just 7 weeks in.
They are not any committment-y thing at this point. They are still just getting to know each other.
You and BF have been building 2 years. You and your GF have been building 7 mos. She has the same
opportunity to build toward something bigger over time with him as they build trust and toward commitment (if they want that.) She just wants everything she wants the very minute when she wants it? Play like she's the only person who exists in your polyweb? Not to have to accept that he comes as a "package deal" and he isn't a poly single without any other partners right now and obligations to meet?
Doesn't sound like she is respectful of him, his life, or the people he cares about then. Sometimes when people bump up against limits they do not like, they call YOU "selfish" because they want it their own way and don't like hearing "No."
Where's the cookies there for him pursuing a partner like this?
MEETING... IF HE GOES
You could let him figure out his cookies on his own. He could cancel the meeting or go. Up to him. If he goes?
You? You could choose to stay home and not attend. He can inform you of anything you need to know post meeting. You don't need to be there front row center if you don't want to be. It is their conflict resolution. Not really yours. You don't sound like you think it is yummy cookies for you to attend and maybe you rather just rest and chill after the club scene last night?
I guess you might be concerned for him since your BF's well being is part of your
business... but you can express concern for him and his well being WITHOUT having to attend this meeting.
Could tell him "I am worried about you and this ex-GF person and this meeeting. I hope you do not get served up another round of drama if you go. I'm concerned and will be here later to talk if you need to air out. But I'm not attending for my own mental health. I am full up right now and prefer to rest, and be of better use to myself and to you in case you need TLC post meeting."
Hang in there.