That must be heartbreaking to see her kids permanently removed, and for he to not make any effort. Mind if I ask what she's on? Your being a good example by taking control of your life. She had the consequence of losing her kids. Does she have any legal trouble? Documented mental health issues? Does she support herself financially? Those are the only routes I can see which might lead to her being forced into treatment. Even if she's went through it before, it's not uncommon for a person to need multiple attempts. Staying in contact to what degree is safe for you, being there to encourage treatment may be all you can do. Doing some research on what treatment options might help her if the chance comes.
I was really sick with drug use a few years ago, and my family got me into inpatient treatment. I was too out of it to realize what condition I was in.