You are really very tolerant boy as you are bearing misconduct of your e sister even-though you have not given any negative response to her. This marvellous attitude would reward you by Allah (SWT). You ought to keep the same behaviour and don't ever think you can get better result reacting badly. Try to share your ideas with her, and appreciate her ideas. Try to talk more with her on different topics. On different eves exchange gifts. Make programs together and move around, it would lead to a better understanding between both of you.