Guys- I don't know what to do?

If you had a crush on a girl in your class and you made many attempts to hint at her that you liked her. But she never opened up to you and never let you talk to her. You thought she liked you back because she would look at you for long periods of time but then shy away.

You tried to put yourself out there by waiting for her after your class was over, but she would walk past you (you never said anything to her but hoped she would get that you were waiting for her). This went on for a couple of months and your feelings grew for her because you JUST WANTED TO TALK TO HER. You were pretty sure she knew that you wanted to talk to her, but she would still avoid you. Nothing ever happened. The semester ended and you haven't see her in months.

Now its been more than 6-7 months since you have seen her, and she randomly sends you a Facebook message. She acknowledges how she acted and apologises sincerely from what it seems. I honestly think she's a b#$tch because she knew the whole time I was trying to talk to her and still ignored me.

What would you do? Should I even respond?