What would you do?

Freshman year my twin sister became good friends with this one girl in the same year as us. She slowly fell in love with her, was crazy in love with her throughout most of sophomore year but went on like she wasn't -like she was straight- and never told her. Now this year, junior year, this friend of hers ends up in my advisory and since we had met multiple times and were good acquaintances, she started walking with me in the hallway to lunch.

I feel as if she is hitting in me at times since a) due to circumstances it is known throughout the school that I am lesbian despite the fact that I never pubicly came out b) I can feel it in eye contact and body language, I have a very good sense for these things, and c) people just know that she's gay.

This bothers me bc people see us (and I've even heard a couple of girls say this) and say/think that we are an item. And I don't like her. I feel like she is somewhat aware of what people think about us, and that it possibly is making her think that we can be together.

But I just don't like her... She's funny as hell, but I wouldn't let her touch my naked body with a ten foot pole. Not to mention that it's awkward considering my sister loved her. From what my sister tells me and from what I've seen first hand, this girl was in love with her as well. My sister would put off telling her and whenever she felt her getting too romantic, she would make a comment about a boy's appearance across the room (my sister actually is bi though).

I feel like I should just tell this girl how my sister liked her, then she'd get the idea and realize it'd be awkward making a move on her twin sister (me). Would this be a good idea?