LR, you asked for my comments on this, so before I log off and take a break from this place for while in order to not rip certain people's heads off, I will answer.
Smack talk about anyone behind their back is problematic, and all too common in today's society. If someone has something to say, they need to say it to my face, at least. I don't care whether it's true or not - the same rule applies. If it's untrue, I then have the chance of correcting their misperception. The problematic part is that if they are doing that about another, then what are they saying about you to others. It doesn't say a lot for the person's trustworthiness to be doing this. It is part of the concept of self-mastery that I believe is really important (along with controlling temper and not knee-jerk reacting to situations). That is her problem, and something that you may be able to educate her on, if you ever get the chance.
The biggest issue, though, is how your partner managed this. If he hadn't managed this badly, none of this would have happened. I am not just talking about breaking boundaries, it's that she had no clue what was going on, and probably assumed the worst.
Taking your issues and discussing them with someone who is not involved is problematic for me too, especially if it is someone that may turn out to be part of a lasting relationship or friendship. He did you no favours by doing this. I will never go bitching to another about an issue that I am having with one of my partners - that is *our* business.
All of this kind of puts you on the back foot with this.
I see nothing wrong with extending a hand of acquaintance with this person, in order to get to know her and find out what her true values are. I would be quite cautious. Is this person poly? If you mentioned that I missed it. If not, you obviously have a lot of work to do.
So I guess my advice would be to try it out, and see if you can get a fresh start with her and do a bit of a reset.
Hope this helps.
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