First off, you're not in love, I think you're merely infatuated with her.
Second, you won't get her back, and if you do, the same thing will happen. She will break your heart... AGAIN!
Third, I make it a rule never to pick up girls at parties because they usually just want a "fling" or "hook up". I don't know if you guys drink alcohol at parties, but it's best to pursue a relationship without the use of liquid courage or liquid stupidity. I usually drink at parties, so that's why I follow that rule when I'm out. What you said really doesn't surprise because you met her at a party (I know people have gotten married to someone they met at a party, anything is possible) but in my opinion, it's very sketchy.
Finally, I will say what I say with all breakup threads, move on. It's not easy, but it's best in the long-run. It's really not difficult to become infatuated with another girl. There are plenty of nice/cute girls out there. Give your heart time to heal a little bit before though because you don't want to use a girl as a rebound. I would wait it off. Best of luck!
I will do my best to reply with an educated, humble and honest answer. Ultimately, it is up to you whether you want to listen to my advice or ignore it completely. Sometimes, my advice may be wrong; occasionally, it will be right. Regardless, I want to do my best to give people answers they are seeking.