I made my sister with an eating disorder uncomfortable while she was making food
I feel like you're being mean to your sister for no reason, why would you make her uncomfortable knowing she has an eating disorder?
I just want to make her feel crappy when she is cooking, it's a part of a grand plan I am thinking of doing.
I feel like your sister is battling something so hard and it is not gonna help her if you will be mean to her. I suggest that you just treat her with respect, or even go out of your way to see if she needs any help with anything, and both of you will have a meaningful relationship.
She gives me headaches and she's not my favorite person to be around. Her cooking is awful too. The plan is essential for her.
She may not be your favorite person but it is still required to be civil and helpful with your siblings, as you do not know how much this must be for her with the disorder and you wouldn't want her to suffer more. I hope you do not go with your plan and just do something that will make her life easier.