I'm diagnosed as Borderline (among other things... I am dsm-iv alphabet soup) and an addict.
In my case, I did things in the following order, and so far I'm clean, and more sane than I was when I first got clean. (I can't speak for the time before I got clean, that's all pretty foggy.) I stopped using, started seeing a counselor and undergoing dialectical behavior therapy- which is a treatment specifically designed to treat borderline personality disorder- and that gave me the strength to go to meetings and find a sponsor in NA to work on stepwork there.
I guess what I can offer is that your sister likely doesn't have control over how she feels from day to day- and is struggling to find it, I know that I still struggle with even knowing what I feel at times, and it is very difficult to express what I don't understand. I find that I have a tendency to lash out negatively when I feel scared or unstable (which is usually
) A lot of the time when that happens, and I lash out, I'm not reacting to a specific person- rather to a situation that I don't have the skills to cope with yet. The important thing to remember is
it's not your fault neither is it hers, but it is her responsibility to learn to live and deal with both her addiction and mental illness.
There are a couple of websites that I turn to that might help you understand what your sister is going through. Dialectical behavior therapy addresses some of the specific skill sets that borderline individuals
tend to be lacking. I can only speak for me, of course, but I find it very helpful as a way to regulate my own feelings and corresponding behaviors.
A website run and maintained by DBT patients Another definition of Borderline Personality Disorder (Personally, I feel that this is 'better' definition of what it's actually like vs. most clinical definitions.)
Hope any of this helps.