How do you distance yourself from a loved one who you can't help, yet, if you keep your distance, you feel as though you're abandoning them?

The loved one in this case is my sister and she is going down the slippery slope and fast. Dependent on Oxy for pain (due to an accident) and is only getting worse. She won’t reach out to anyone else (feels ashamed), so, she turns to immediate family (namely my one brother and I) for support. The back pain is a major problem (doctors won’t do surgery and she needs to take the Oxy), but, the dependency is becoming a bigger issue. She’s falling apart. There is nothing that I can do for her. Now, she mentioned to my brother that she is a borderline alcoholic (alcohol helps with the pain, since the painkillers alone aren’t doing the trick). My brother (who also messed his back up and is disabled) said that when speaking to her, ‘it’s not really her” (it’s the addicted her). I know that she’s sick.

I’ve been under a lot of stress because of this. It’s been so stressful, that I believe it is making me sick. Other than my brother, I’m the one that she turns to. Not her husband, she’s distanced herself from her friends, she won’t open up to my Dad, my Mom passed away 3 years ago, and that was a big support for her. I know that she can’t pull out of this alone, but, I really don’t think that I can help.

Also, she’s is right in the midst of a lawsuit (because of the accident), so, she has to be awfully careful what she does.

I hate dumping on you guys, but, I don’t know what to do. Any advice?