SRiddles, I think I may understand what is making you so pissed.
I had something simular (but also very different) happen to me years ago. An old friend, someone I liked a lot, but knew had many “issues”, involved another friend of mine in some of her crap. This person had no idea what she was like, and was risking getting himself in a sticky situation because of her. It’s a long story, and even involves actor David Hasselhoff as a minor player in the whole story (really, I’m not kidding about that!) The point was, it was one thing for my screwy friend to give me or her other old time friends her crap - we were used to it. But I sure as hell wasn’t going to let her involve some innocent third party, another friend of mine, in HER CRAP!!!
Do you understand what I’m saying? You know what your sister is like, you can cut her some slack, and you love her, because she is family. But you don’t want her messing with innocent third parties, i.e. Sam and his S/O, also a friend of yours.
My solution with my friend and the David Hasselhoff fiasco was to go behind her back (yes sneaky bitch that I am) and tell my other friend what a flake she was. In other words, gave him the “heads up” about her, also explaining that she was a nice person, but had many “issues”. It did the trick, he was warned, and never came to harm because of her. I had decided to give my friend the “heads up” only after talking to her, and realizing that no matter how appalled I was, she was totally clueless and selfish, and would never be reasoned with. (But I did try to deal with her first.) Your mileage may vary, you are in a different situation.
There is no excuse for her passing along the misery by hurting other people (or attempting to) because of the hardships she has had. If we all did that, things would go to Hell a lot faster than they already do.
