Hello, and answering your question: hardly would sisters actually be this intimate or even like each other. You make sound that you are a woman, too, and best friends can get intimate. If she knew of your sexuality before, this does sound like some sort of "provocation". If she didn't and now she does, this may stop. If she's straigth, there's little you can do, but to accept her friendship, but with a more "respectable", not so intimate approach (would be better for you). Now, if you're both homosexuals, then it's clearly something else, and, I daresay, something wrong. I advice you to check the possibilities I listed and choose one of the advices (either put limits to your interactions, or actually explain to her how you're feeling and how she needs to be different with you if she really doesn't want more than friendship).Best of luck and happiness to you.
