My family doesn't trust my sister

I'm a 23 year old female.My sister is about 4 years older than me. We grew up mainly with our mom, but the weekends our dad had us we saw his struggles with addiction. My sister moved out of our moms house and in with our dad and my sisters boyfriend when she was 17, when her alcohol addiction started. 4 years later, our dad went to jail, and her relationship turned abusive after they both started using meth. I lived about 8 hours away and she would often runaway to stay with me to hide from him and detox. This happend from the time I was 19-22. My sister and mom would call me crying throughout those years. They have never really had anyone else to talk to who wouldn't judge them and would openly listen, so I've always had all of their emotions dumped on me. When I was 21 and my sister was 25 our grandmother, our dads mom, passed away and it was extremely difficult for my sister. She spiraled back into bad habits for a but for about the last year she has been clean. Her boyfriend went to jail and she was able to pull herself out of the lifestyle. Around the same time she got clean, our nana, our moms mom who my sister and mom live with, was diagnosed with cancer. My sister became our nanas main caretaker. My moms 2 sisters and 2 brothers HATE my sister.They've tried multiple things in the past to get her in trouble, and this past week they went into the house, took pictures of my sisters room and are trying to say shes on meth again when it's just essential oil