Hi, I'd like to help you with your question.
It is hard to say for sure what is wrong without being able to see your sister for an evaluation, but it sounds like your sister has an anger issue, possible intermittent explosive disorder. She may also have some personality issues, maybe even a personality disorder. She most likely used the alcohol in the past to help her control her emotions and now that she does not use anymore, she is having trouble handling how she feels.
Getting help for someone who does not want help is not easy. If she is refusing to go to see a therapist, then the best you can do is be supportive and continue to suggest help to her. She needs to see that her problems originate with her and not with other people. And until she understands that, she will not want help.
You can also help by allowing your sister to deal with the consequences of her behavior. I know that goes against your nature, but it is ultimately what needs done. If you allow her to cope with her own problems, she will be able to gain insight into how her behavior affects her life and those around her.
If your sister talks of suicide and you feel she is serious, then you can call the authorities and have her 302'd. A 302 is an involuntary commitment to a mental health facility, most likely your local hospital. The person that hears her threat is the one who needs to commit her. She cannot be committed based on hearsay. She can be held for 72 hours unless a judge deems her a danger to herself or others. In that case, she would need to stay longer.
Here is a clinic that you can take your sister to. They are funded by the government so they can charge on a sliding fee scale. They will be able to do an evaluation and determine your sister's diagnosis and offer her the appropriate treatment for her situation. Here is the link:
You can also contact the United Way for more resources in your area, including support groups and financial assistance.
I hope this has helped you,