That's difficult. My mom is also dealing with a lot of pain, but there's nothing I can do for her. I'm tempted to feel guilty over her pain, but the truth I have to accept is that she is the only one who can make her decisions, and I can do nothing for her physical pain. And I live with her!
While it's hard to accept, the truth is each person has to make their own decisions, choose their own beliefs about others, be responsible for their own care. It sounds like you're showing you love her, and she needs to understand you can't just leave and go to her, you have a life you can't always leave.

I hope her surgery goes well, and that you can feel better about this.

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Matthew 11:28
Come to me, all you who are weary and burdened, and I will give you rest.</font color=green> Sounds good...