my pain goes on

Honestly I'm not sure what i'm expecting to find here but I can't talk to family and friends so I guess I feel isolated.
I'm a mother of three and nanna of two little girls. My eldest (32) and youngest (24) are both addicts. I know for the youngest it's crack. My oldest uses this too but I'm not sure what else. Mind you I'm suppose to be too stupid to know this.
Iv seen their pipes even though they think they hide them pretty well. My youngest also has an anger problem and if I ask her whats wrong she flys off into a rage.
my eldest works full time but when she comes home from work her 8 & 11 year olds are pretty much by themselves as she will sleep the moment she gets home and until she wakes up on the couch early hours in the morning. ?The 8 yr old more often than not stays asleep on the couch sometimes without a blanket and not in her bed.
Yet their mother can be awake from thursday night until sunday night. I'm lost, we live in a granny flat at the back of our house so i can keep an eye on the girls as long as my daughter dosn't think I'm interfering, then we all cop the brunt of her anger.
GuessI just have to keep doing the best I can which is so hard. I have survived two strokes in recent years having left sided paraylis so i'm not always that well myself and this situation is so stressful but I can still laugh so on I go.