How to ignore her without being rude?

Anonymous
Okay, long story short: I used to know this girl in college and we talked a lot and sat next to each other. I became interested in her and we went out a couple times and after that she started being "busy". Then she stopped talking to me altogether when school ended and when I re-initiated and asked her if she wanted to meet for drinks to catch up, she didn't reply.

It took me a long time, but I got over her.

Now just a few months after getting over her, it turns out she's in the new program I'm starting soon. The school sent us a class roster and she saw my name on it and texted me saying how she didn't know I was going to the program too and that she guesses she'll see me at orientation. I didn't reply.

I REALLY don't want feel like talking to her again. I was feeling so great, feeling myself again, feeling good about everything, and I don't want to go back there to those hard times. At orientation I don't want to talk to her. During classes, I don't want to sit next to her. I don't want anything to do with her and yet here she popped up just as I was getting over her.

Orientation is next week and classes start soon thereafter. Can anyone give me some tips on how to handle this situation? I don't want to talk to her and if she talks to me, I don't want to come off as the boring guy she probably thought I was; I'd want her to give the impression that I've been busy and feeling great, which is true. But I fear the fact I don't want to talk to her at all will make me come across as "bored" and thus confirm her faulty image of me. I also don't want to sit next to her after sitting next to her that whole time that semester.

Maybe it won't be rude since she didn't mind dropping contact with me for so many months.
Updates
+1 y
I'm afraid if I act friendly and polite towards her, I'll start caring about her again.
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+1 y
I really don't know why she bothered texting me. I would have had her rather just ignore me like she was doing all this time. I mean, seriously, after giving me so many "busy' excuses, and then finally ignoring me, I can't really believe she did that.
How to ignore her without being rude?
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