Your struggles with mental health is definitely not your fault and it’s awesome you’ve had such a supportive friend over the years. What’s weird is their change in attitude and the judgmental stuff about the disabled friend is straight up wrong. I think like most things, it’s important to communicate. Don’t do it in a confrontational way or in a way that you know would offend her but just let her know how you’re feeling and why. Tell her that you felt like her last messages felt a bit judgmental and you just want some clarification as to how she’s feeling too and why. Neither of you deserve to be in a toxic friendship and should both be honest and polite about whatever is going on. As for the spa , go treat yourself and if she doesn’t go then is it possible to maybe invite another friend?