What am i to her?

so this girl is my sisters friend and one night round my house we got a bit drunk and ended up messing around a bit. I ended up falling for her, i spoke to her a bit after that and we hung out a bit and she got me doing things she likes and she seemed to pay more attention to me than before. i text her what to do about the night and she said "i think we should leave it" so i did and stopped talking to her. Weeks later she commented on one of my art pieces that i put up on Facebook and how impressive it was and that she wanted to go to my exhibition with me, we spoke more and sent a lot of mixed messages and then she went to the exhibition with me and my sister came too because there friends (originally meant to be just me and her) she wore a very nice perfume and looked very attractive she seemed to want to be close to me most of the time. After that we spoke a bit but recently she's been ignoring me and seems to have a boyfriend.

The mixed messages being liking my statuses and art work and congratulating me on achievements when she doesn't do that to anyone else. Also she rarely text me first or asked me questions. Its driving me insane because i really like her but i don't want to hurt myself over liking her.