My heart goes out to you. How hard it must be to be so aware of your situation, trying to improve it and have others live the extreme opposite, especially while dealing with recently being sleeved.
A few things,
1) You seem to be quite young, thank God that you did not get caught up in this for the rest of your life. You are stopping that chain , that life cycle of dysfunction. Many of us have families living in these same situations. I am 47 years old and wish I stopped abusing myself long ago with food. My father died of obesity related illnesses and all his siblings. I was right there with them for years. So give yourself some credit, you are doing something for them. Be an example. Be loving to them but make good choices for you. You can not change them, and it sounds like they don't want to change.
2) I hope you understand how this relates....
Three of my siblings died of drug related incidents. I really was bitter with them for some time, without even realizing it. I did not understand it, I was so bothered by seeing my sister wither into a shell of who she was. I was a lot younger and very impressionable. I was experimenting with things I shouldn't of been also yet I made different choices and by the grace of God had the will to stop.
My point is this...I now look at there lifestyles as a lesson to me. When they died like that it was not in vane. Do you understand? I might not always no what I want but I sure no what I don't want. I did not want to go out like that. Looking at them in this perspective, allows me to live free of that lifestyle. They showed me very well what I did not want to end up like.
Your family is actually showing you something very powerful. I know you want to save them and it hurts terribly but you can't honey.
Don't be angry with them, it will eat you up. Love you Mama while she is here. Show your sister how she can recover. Pray!!!!
-Sorry to go on and on....