Small town- you are definitely not a nobody. You care- and feel helpless.. only your sister can control what she does- except for locking her up- there in nothing anyone can dfoto MAKE an addicted soul stop- unless they want to. I am an extreme example of that (now 16 months sober- but I had to lose everything first- including my life). You can offer support and be there for your niece and her safety. You need to focus on you. What are you doing to cope with this? It is a trap to think 'I should not be getting so unwell over this- I am not the addicted one'. Addiction casts a wide net with damage done- like ripples in a pond from a stone dropped in the middle. The best way to help your niece- support your sister and others is to firstly look after yourself. Addiction is great for identifying rescuers- those who pick up the pieces- gives the addicted person more time to spend on getting their high. Tough love....I cannot add any words more wise than those offered by others. I will offer empathy and support.