Sorry for bad grammar, I tried my best.

I'll try to put it simply. I broke up all contact with my female friend from the college. Long story short - it was kind of a friendzone. A lot of attention and affection from my side with kind of zero respond... She had a boyfriend, I'm sure she knew I was into her and she used it many times to make me feel sad. After a few disrespectful behaviours from her side I decided to cut off all contact, it was a good occasion to do that, because it was the end of the semester with no any opportunities to see eachother until october (3 months). So far I didnt text or call her for about two months, neither she texted me. I'm sure she knows what's my pain because I tried to explain it to her several times, what I regret now. It's september now, I'm sure she will contact me somehow soon and I'm also sure that she will act like nothing happend (like she always used to), willing to keep this validating her relation. How should I answer to her random "Hi whatsup :)" not showing any butthurt but also letting her know that it's NOT going to be like it was. Unfortunetly we are in the same group on our studies, it means we are forced to see eachother at least 8 hours a week so I really want to get out of this situation with face. Thanks for any answer.