Bipolar Disorder Support Group
Bipolar disorder is not just a single disorder, but a category of mood disorders marked by periods of abnormally high energy and euphoria, often accompanied by bouts of clinical depression. This is the place to talk about your experience with bipolar disorder, learn from others' experiences, and find support.
Considering your past, shared unpleasantness and your hesitancy when it comes to risking being hurt again, I think it's only natural that it cross your mind that she might be doing this for some less than noble reason.
The objective truth is that you have no way of knowing her true motivation for declining your invitation.
Either of the possibilities that your friends suggested as being her reason could be accurate.
Better to err on the side of kindness. Since you don't know differently, give her the benefit of the doubt. If she's a 'rat', you'll find out sooner or later. Unless and until then, take her at face value.
If you notice that you can't let this go and keep wondering as to her motivation and suspect that she most likely IS doing it to test you then, yes, THAT would be paranoia.
I think you handled it very nicely.
And HAPPY BIRTHDAY!! I hope you have a wonderful time with your friends!!!! (((((Hugs)))))