I agree with greeklawgirl, if you were invited to pref, they must already love you. Sororities don't just invite back girls to pref and then drop them. Just stay calm and look around. One thing a lot of people say to do is to look around at the other rushees that are there, since those people will likely be the new member class for that sorority
Kinda exciting how it all comes together huh? I am sure that you will soon have a house full of new sisters and that you will have the time of your life!