My mom does this "woe is me" BS. I just stopped being around my mom as much and took her comments for face value and actually responded directly to what she was saying.
Her: I just want to be a good grandma!
Me: Yeah, I want you to be better too, but you keep ignoring everything I say, keep it up and you won't even have a chance to mess up. shrugs
After about 6 months of it she realized that I'm not her teenage son anymore and that if I don't want someone in my life then I'm gonna make that decision. And yes, I realize that most people wouldn't say something as direct as that to their mom, but I've been dealing with stuff like this for years.