Has your elderly parent turned your siblings against you?

I work (no pay) for my mother 24/7. When I moved in a decade ago it was mutually beneficial. Now that she is 87 it is a different story. I try to lovingly support her, get her to doctor's appointments, fix her meals monitor medications, etc. the older she gets, the more demanding and eccentric she gets. I have no life. I have two sisters and a brother in town. If Mom and I have any argument she immediately calls them and exaggerates beyond belief. One time she told them she was afraid for her life! She also tells them that I sponge off of her which is completely not true. I pay a lot of the household bills. Financially she could not make it without me. My younger sister believes nothing because she knows what is really going on. My older sister and brother believe everything and treat me with disdain. The only time she ever talks to them is to talk about me. I now feel uncomfortable attending family events because they make derogatory remarks towards me. They will not, however, help her with any of her needs...nor do they stop by and spend time with her or even call. Do I even worry about this? I already feel so alone- now this.