Help me get over her.?

Me and this girl have been friends for about 2 years now. I've been infatuated with her since early on in our friendship, we met in cl and hit of well and are similar in some ways. I told her I had feelings for her and she declined (she's never had a boyfriend, or even a kiss). So I let it go and we still were really good friends, time ped and she decided she wanted to go to prom with me and I was cool with that. Things got awkward over the summer because I drift away from people, I always have. I told her that and explained it may happen, but I will always make an effort to come back, and I have greatly. The problem is she is emotionless basically 2 years later we are very very "edgy" friends. Lately I have disliked talking to her because she always finds a way to make everything negative. I bought her a Christmas gift to try to soothe some things out and she just told me she didn't want it. I'm ALL for getting over her, but the problem arises that I sit beside her in 2 cles, as well I want to tell her unless she starts to be a friend at least, we're not going to prom. I figure to wait a couple weeks till this semester is over so I don't have to deal with sitting beside her and it being awkward. So what can I do for these next couple of weeks, do I ignore her?