Thank you for opening up to us about your concern. I think the first thing to do is to find some friends you can talk to, or a therapist, who can start to help you sort through this long-standing reaction with your mom.
It is time for you to have a plan to move out. Even if the plan scares you, you still need it because living with your mom keeps both of you dancing in quicksand.
Becoming more independent and dealing with your mom are the important goals. I would rather see you struggle with feeling guilty about not helping her, rather than trying, failing, and then being blamed. Right now you’re looking for detachment.