Dealing with Family Who Don't Understand My Chronic Pain

It sounds like she's committed to misunderstanding you. No matter how reasonable you are, you can't make her understand if she's decided to refuse to understand. The only possible solution I can thing of is, Has she said why she keeps asking you this? Maybe she would be happy spending time with you in a different way. But I don't think it's your responsibility to make her understand. It's up to her at this point, you just do what's best for you.

Honestly everyone is different. Some will understand and some won’t. All that is important is you stick fo your boundaries and continue to advocate for yourself. Remember you are doing nothing wrong by saying no.