I have a problem hard to explain, heart or head?

i was adopted and love my parents emensly. (i hate my birth parents) the problem is my adoptive sister and i can't get along, she says im a prick and i see distance and superficial care in her eyes. i have to see her next month because her and her kids are coming back to Canada for the summer. life is bigger than her and shes not me i see distance in her eyes thats emenant of gest, any suggestions? please no crude remarks, i really am on the brink.