My mother has a sickening addiction ... time for an intervention?

My mother has a sickening addiction to methamphetamine. Our immediate family is well aware of it, due to her stealing from family, not working for months now & still managing to miraculously pay bills, buy gifts, etc. My mother and I are very open & we have discussed her situation. I'm defensive for my other family members (and myself) that she's stolen from, with tact. (That IS my mother.) Her boyfriend and her inform me when she's so sick from being without her "drug". Both of them are users and neither of them are working to correct their problem ... if they even see it as that. It's breaking up our family & I'm torn in the middle, trying to do the impossible and defend/please all parties involved. I'm pregnant & it's getting to the point where I'm tired of being nice and wish I could consciously decide to cut that out of my life, but ... it's my mother. It's a very hard decision ... & everyone is hoping I can find the solution. What do I do?
Ok ... her boyfriend and her are already in that 3rd stage of addiction. (I'm almost 100% sure that's how things get "paid" amongst their life.) Also, I'm 25. Parents divorced when I was 2 days old. (So, Dad's not going to be into "team playing".) AAAH yes ... and she's been to rehab before. I've cut her off from my life before. She's been to jail and "supposedly" was clean throughout her whole probation. Her boyfriend and her are already entering the early stages of their abusive relationship & having had that experience, I know the added difficulty that it adds to the situation. I believe she is in control, though, not him.
Not to mention, you can't exactly "admit" a full grown mother, that may/may not believe she has a problem. She has to make that decision.
I don't live with my mother, lol. Did I sound that juvenile? I have my own things to tend to.

: http://alcoholdrugstreatment.info/my-mother-has-a-sickening-addiction-time-for-an-intervention