oh gimster,I'm so sorry your heart hurts as you say! You ARE doing everything you can! It would not do for you to make yourself unstable to help her! What would she want? She would want her child safe and stable and "ok." Every mother wants her child to be so and I'm sure you were not her "less loved child!" Sometimes we give attention to the children who need it the most and forget to notice the child that can do things on their own! That does not mean we don't love them, although they feel we are not interested. It means we know they will be alright! This could be the case when you were young!
It hurts, yes, but again, it's not your fault! You are doing what you can and somehow, your mother knows your love is there, I can tell by how pure it feels when you write it! I'm sure she can feel it too.

Warmest regards Gimster,
dancer9