How do you deal with toxic mothers?
Hi, it is very nice to meet you! You ask an excellent question. It sounds like you struggled a great deal while growing up with your mom. Dealing with a parent can be a very difficult task. Given that you are now an adult, you are now much better able to set boundaries with her. You have every right to set boundaries with her, even if she does not like or understand them.
If you and I were working together in therapy, I would want to explore more about your childhood and how things were for you growing up. You went through a lot, I can only imagine how upsetting that must have been for you to be dealing with appendicitis, which is an emergency, while mom was focused on the false thought of you being pregnant, which you were not. It sounds like your mom has a lot of her own trauma and issues and projected it onto you, and now is doing the same with your younger sister. Mom lives in a heightened state of fear and anxiety. That must be very stressful for her and everyone around her. Also remember that none of the things that happened while growing up where in anyway your fault. You did not cause mom to act this way.
I would encourage you to set clear boundaries with her regarding what is and is not acceptable behavior. She will very likely not like it when you do this, as she is not used to it. But, she will adapt and adjust to it, the important thing is to maintain these boundaries. Depending on how old your sister is, I would try to support and encourage her to also set boundaries.
I hope that you have found this to be helpful and I wish you all the best moving forward on your journey.