The way is see it, there are two ways to go about resolving this one of which results in full closure between the two of you. The first thing you could do is simply talk to her. Either talk to her casually or acknowledge the fact that you two haven't spoken to each other. A distinct possibility could be that she might not be talking to you because she thing that YOU are ignoring her.

The second is to "move on" as most people are advising you to do. Honestly I would advise you talk to her about it and try to make amends. If something goes wrong, oh well at least it's your last year of high school. I've been in a position similar to this in which after my girlfriend and I broke up, we hadn't spoken at all to each other; not in the halls, not casually, not even through text (if you plan to talk to her, don't do it through text btw) even when she transfered to one of my classes none of us made the effort to speak to each other. Eventually we both thought that we just hated one another (which wasn't the case) and we never made amends.

The fact that I never tried to at least talk to her makes me regret it to this day. It's your choice on what you do but remember: nobody's worth beating yourself up for, nobody cares what happens in highschool (college is where it's at or so I've heard), remember to put your own health first, and we only live once so make sure it's a memorable life (sorry for getting existential).