abusing drugs

so 2 of my sisters are using again.
they've had 18-24 years of clean living.
i noticed a couple years ago a slow spiral downward for one of them, and more recently a downward spiral for the other.
it's quite sad really.
i honestly believe they will die. drug addicts lie, cheat, steal, get better, or die.
when i was younger, still a teen and young woman.. much of my free time was spent with my oldest nephew. he was the love of my life. his parents were both active addicts, so i wanted to be there for him............i wanted to keep him safe. he spent nights with me some of the time while i still lived at my parents house. i took him swimming, to the movies.......anywhere and everywhere. i spent as much time with him as i could. i didn't want him around the lifestyle his parents were living. i wanted him to have someone he could count on.....
luckily his parents got the help they needed and for most of nephews life, they lived  clean productive lives  and provided a good home for him. a great home actually...
I feel sorrow. i feel sad for him. he's grown now so i dont feel like i have to protect him. i just wish it could be different for him.
i also worry about my parents.
i'm sure they thought all those bad times were over with.............they could sleep without worrying about getting "that phone call."
i don't even know if they know what's going on..........though i'm sure they have their suspicions. all you have to do is look at either of my sisters and you can see the affects...........they both look like old women.......old, underweight, tired women. a year ago they were attractive, middle aged women. unbelievable.
i can't protect my parents or my nephew from our new reality.
i can't make it go away.
i love my sisters. they're good people with a serious problem.
i don't know if i believe in God.
i believe in praying though.
it's all i have. it's all i know to do.