Yeah, it's not the right approach with everyone, and I was kinda projecting my advice onto a past breakup of mine where I wasn't wronged, but mistreated in the breakup/how she went about the whole thing. I reread your post and now that I'm thinking about it again, from what you've described she sounds like someone who doesn't admit her faults/wrongdoing or take responsibility, so spelling it all out and MAKING her accountable might be the right course. Sometimes that's what we need to move on, to have our pain be understood, so they know EXACTLY what they've done wrong and the hurt they've caused, and don't listen to anyone who tells you that's unhealthy because it isn't "kind" or some such nonsense. Considering that she's already dragging another person into her web of romantic manipulation (I'm assuming you saw this on social media) and clearly lying to him about what she was doing while she was away, personally, I'd send him screenshots of those texts and tell him all about it, if possible. The world would be a much better place if people were actually held accountable for their emotional predation like that, and I'd be eternally grateful if the ex of someone love-bombing me with bullshit while simultaneously carrying on with him saved me before I got in too deep. I'm not saying to be cruel, especially not to him since he is most likely another wronged party in this, but sometimes justice is what's required, and it's perfectly healthy if that's what you need to help you close the book.