I'd also like to point out that your grades aren't horrible. They aren't superb, but they're okay. I know at my chapter our grade cut was a 2.5; anyone below that got cut immediately no questions asked. The ONLY exception was a legacy who always got a courtesy invite to second round. So, just because you're a 2.8 doesn't mean you WILL get cut immediately, it's just a maybe.
So my advice to you is to just take a deep breath and relax. If you are tense and nervous when you go into the parties it will show and you might come off as weird/freaky/annoying/aloof/stuck-up, etc. - all of which will get you cut way before your grades!
DISCLAIMER: I did NOT attend UCF so I am NOT representing the Chi O chapter there with my post!