drugs and their mental, physical, and emotional control over a person?

My mother has been addicted to meth for going on 4 1/2 years she has tried programs, counseling, and a few other things. Yet, she tells me that she can’t help it she can’t do anything without thinking about it. She has even cried to me asking me for help because she hates doing it, what she does to get it, and not being able to function properly on a daily basis without doing it. Even thinking about how much damage it’s done to her it only makes her want to get more. she literally has nothing now she is in jail doing a program, but it hasn’t owrked in the past. I’ve done alot of research and there aren’t that many people who recover completely from addiction to meth. many of them have relapses even if it is years later. Is there anyone with any experience in this matter who could share some advice?
I didn’t always help my mom she was out of my life as well as anyone else that I knew for about 2 1/2 years. She came back to my life in May 2004.She has actually tried to dissapear again because she says she hates for me to see her so weak and unable to control herself. She used to be such a great person, actually she still is. I can still catch a glimpse of my real mom in her whenever she holds my sister. Even til this day she won’t tell me why she started. She says that she doesn’t remember. which is true her memory is horrible now. I’m actually so scared that she’ll leave me again. I’d rather have her in my life with drugs than to not have her.