You are doing the first part of a long dance, keep calm, strong and really listen when she speaks. You do not have to agree with her, in fact do not agree with anything you do not agree with for the sake of validation. Validate how she might feel that way, but do not agree with the BS.
Also, do not rely on the MC to "expose" her. She has to figure this out on her own, and she will slowly start to do that, and I think she already has. The MC will likely validate her feelings by turning on you every now and then, be sure you are ready for that.
My point to all this mess of a post is to expect this to be a long road and DO NOT rush it. But I think you are doing great, as far as the trip is concerned, she is open to you going and you said you do not trust her, but you do not want to keep tabs on her, this seems to be oxymoronic, You can't control what she does, but I think it was a great start for her to invite you with her.
