For the last two years, ever since she got married, my sister has only spoken to me about twice a year. She rarely discussed how her life was going or what she was doing. About a week ago, she called and told me she was getting a divorce and needed somewhere to stay. Of course, I said she could stay with me until she got back on her feet.

Gradually over the past week, she's been revealing details about herself. Firstly, that she has been diagnosed with BPD and hasn't been doing anything about it. Secondly, she has been addicted to a variety of drugs in the past two years. She says she's 100% off of everything now. Thirdly, her marriage has been over for a while and she didn't tell anyone in the family; she has a new boyfriend who enabled her drug habits. She also alternates between crying about how much she misses me and how much fun we'll have together, and cursing me out for being judgemental and "hating" her when we were children together, often bringing up events that I don't remember happening at all. There isn't much middle ground between these two moods.

I am completely lost. I have never had to deal with drug problems among my friends and family, and I'm not sure how to react to her mood swings.

The way she's acting, I'm afraid to have her in the same house as my husband and young son, but she doesn't have anywhere else to go. (She refuses to live with my parents--she says they're emotionally abusive, though in my opinion, my childhood was completely free of any form of parental abuse.)

So far, I've found the best psychiatrist and therapist in my area for her, and I'm going to try to pay for as much therapy as I can, since she's uninsured. I've also looked into rehab programs in my area, in case she needs that. Is there anything else I can do? Does anyone here have tips for reasoning with her or getting her the help she needs? Are there support groups for this? Book recommendations?

Thanks for reading this rambling mess.