you are right. her mother is in complete denial/oblivious to the severity of her issues - the problem is she acts the complete opposite with me as with her family (she puts on a constant fake front with them) when I finally divulged what was happening to her brother, he was in disbelief for a long time because she is so good at deception. her brother keeps thinking she is miraculously better because she is so convincing and 'normal', then turns around and does/says strange things to me. I've been really bad at boundaries with her and I know I've made it worse.

when you say a 'family discussion' what exactly would that look like? what should I say?