For context I have an older sister (20F) with OCD and an Anxiety disorder. I (18F) am autistic, aspergers syndrome so not seen as autistic autistic. My older sister is belived to recently have developed both of her disorders due too being locked up during covid 5 years ago. I have had mine my whole life. She's supposed to be taking Anxiety meds but stopped due to them making her sick. We share a car together but recently she's been difficult about it. We work about the same distance from each other, but she takes the car every Monday and Wednesday to school (45 minutes one way) she won't go to the gas station by herself and yells and argues till my mom makes someone go with her and usually I'm the one who has to go with her even if I already had plans, if I'm out with my boyfriend I have to come home early to take her to the gas station. Even though she works right next to it and can fill up before or after work with 0 inconvenience. Today I had to go to work so I asked my older sister if I can take our car to work because she works at 12:45 and I had work at 11 and I'd have to move her car anyway because it blocks my moms car in so it was easier for me to just take our car and her use my mom's. She told me "No, because driving to your work uses more gas then driving to mine" (my work is 2 minutes further then hers) which I guess isn't wrong but I asked my mom if I can take mine and my older sisters car because It won't be an inconvenience to anyone. She told me no too because "your older sister gets nervous driving my car just take mine" I got mad because I've had to suck up every issue with her and told to just deal with mine while she gets princess treatment. At my grandpa's retirement party I had a meltdown because of a humming industrial refrigerator. And got yelled at for 20 minutes for being "Selfish" and not dealing with it. Meanwhile I have to bend over backwards if my older sister has an issue. It's not even the fact she has Anxiety. My issue is she uses it to her advantage. She's not uncomfortable with my mom's car, the car was never an issue unless I want to use mine for something. My older sister bought a car she's absolutely in love with that's currently at the mechanics for the past year because it's a rare and hard to find parts for car. She's never even gotten to drive it because the engine overheated and warped all the parts in the engine. She's expected to get it back in a week or 2 but I already know she's going to hate driving it. It's from 1994 and it's an absolute boat, I call it the beluga whale. She hates driving large vehicles and is scared of driving in general. But I know she's gonna suck it up because this cars worth 24k and she likes the rare factor. It was never about her disorder it's about her being stubborn and I guess I'm being stubborn too but my family picks and chooses what disorder to attend too. And if I call out favorites I get told I'm just making shit up and she has more issues then me and ive learned to work with mine so i need to work with hers. I've already talked to a few of my co-workers and they have all said I'm not an asshole and my family is playing favorites but I still feel like I am the asshole.