My sister has been diagnosed with borderline personality disorder. I have read up a lot about it but what I can't seem to find is advice on how to interact with her, especially when she is being challenging.
She started to go off the rails a couple of years ago when our mother who supported my sister a lot had a series of strokes and had to move into supported housing. My sister has always had issues with alcohol but when mum wasn't there to help she hit the bottle hard, got a series of convictions for drink driving, assaults etc., lost her job and had her children taken away. She also alienated nearly all family and friends with just sheer nasty behaviour - making up stories about people, bombarding people with phone calls and texts attacking them etc. She also took a lot of my mum's money (tens of thousands) which left her with reduced choices about her care. I've been on the receiving end of a lot of this too, but I have always understood that she is unwell and now she has this diagnosis it's like a feeling of relief that finally someone is making sense of why someone who is intelligent, charming and beautiful can be such an utter shit to the people closest to her.
The thing is I don't know how to respond when she starts the attacking behaviour. Most people have just cut her out of their lives and that is tempting, I know DH would prefer if I did. When it comes down to it though she's my little sister, she's unwell and I don't want to walk away. I find it hard to get past three things from the past - taking my mum's money, ruining my wedding my trying to get off with my teenage stepson, and telling various family members that my late miscarriage was caused by DH hitting me. These seem pretty much unforgivable to me, though if she at least acknowledged that she had done wrong that might help. I have tried to be supportive but our most recent interaction was a long text where she accused me of causing her illness by bullying her, and then tried to stop her ex H from letting me see her children (he told her that their relationship with me is separate and she can't use them as weapons, but I really care about them, they have suffered a lot from their mum being ill and a drunk and I am hurt and angry that she won't put their needs first).
Can anyone with experience with personality disorders advise me how to move forward with this? I should explain that she isn't currently drinking as far as I know, she did residential detox and is on a medication for recovering drinkers which makes her sick if she has any drink at all (forgot the name of it) so I'm pretty sure she's staying dry. I just want practical advice if possible on how to manage to have any boundaries in my relationship with my sister and how to support her without having to absorb a lot of crap. Thank you for reading this.