How to respond to a meaner older sibling (with respect in mind)?

WOW..you are very mature for your age. Try calmly asking your sister if she would be willing to talk to you in private, talk about how she is going to be leaving the nest soon and about how you want to be on good terms with her. Tell her that she is hurting you by being mean and then tell her you are sorry about all the stress she is going through but that you are there for her. After all is said and done, ask her for a hug. That's what I would do. I have an older sister also, she is the oldest and I am the second of the 6 kids so I know how tense things can get.. Hope all turns out well indeed.