You said you can convince her to get help, but you're not comfortable talking to her about it, right? (just want to make sure I understand you) It sounds like it's time to enlist the help of another family member, and talk to her together. Or, how would you feel about writing a letter to her about your concerns?
When she's under the influence, it's very likely that she won't remember something she is told or something she is supposed to do.
Good luck to you!
Maybe you can attend a Narcotics Anonymous group for family members of people addicted to narcotics. Since you are not comfortable confronting your mother, they may be able to provide ways of approaching her. You can also look in to staging an intervention.
I'm so sorry your going thru this Daniel. It seems like the tables are turned now and your the concerened parent hay. A lot for someone to handle. Your mom still loves you and your brother, she has just lost her way right now. Too bad the boyfriend wouldn't end up in jail or someting for a good long time, then maybe your mom could get her life back. I am just 16 days free of vicodins and I know it is hard, but you have to put your mind to it. I think that the advice before this was good. Write a good heartfelt letter and tell her all of your fears and hopes, concerns, regrets, prayers, etc. whatever you want to say. It is easier to write, that is what I do so that I can get everything out, otherwise if arguing happens, nothing gets said. One of the things that scared me was thinking about the laws I was breaking and how the pain pill thing is such a huge problem right now, the cops want to bust everybody selling/buying these things. They are felonies, and if your mom gets caught she could be in big trouble and going thru withdrawls in jail will be very, very bad. Keep you head up Daniel and never stop trying to help your mom to come back. I know you would never want her to get into trouble, but too bad you couldn't somehow get the so called boyfriend in some and get him out of your lives. I'm not suggesting anything, just wishful thinking I guess. Hang in there and I will keep you in my thoughts and prayers.