Girl advice. What in the hell is going on here?

[True Gentleman]

Please bear with me, I know this is long, I just really need some help. Thanks

Okay so I met this girl, lets call her "Gabby", through a group of friends a few weeks ago. Was just trying to be friends nothing more. So my friends and I invite Gabby and a few of her friends over to our house to pregame a few times and get to know each other better. The next day Gabby adds me on facebook and is constantly messaging me for hours. The next day she gives me her number, without me asking for it. My fraternity had a party that Friday so I decided to invite them all. Gabby and her friends show up and she starts flirting with me, a lot. We eventually start dancing together and move on to making out, plus a little touching. Gabby seemed really attached and was making sure she held my hand wherever we went. We eventually leave the party and she insists we go to this bar so she can dance with me. We go to the bar and the dancing gets pretty dirty, accompanied with more making out and touching. She invites me back to her apartment, but instead we go back to my place because I live a lot closer. She sleeps over and we end up fooling around for hours in bed. While we're messing around she keeps telling me how she wants this to become a usual thing and how we have the entire semester to mess around together. I drive her home the next morning, because she had to go home for the weekend & there is absolutely no awkwardness. Before she gets out of the car, she leans in for a goodbye kiss. The next day she texts me every 5 minutes for hours. The day after, Sunday, I text her and she just responds with one word answers or stuff like "hahahaha". So last night, tuesday, she was texting me asking if I was going out. She told me that she would text me when she was at the bars later on because she was going out with some of her female friends. She eventually doesn't text me, so I texted her asking if she planned on going. No answer. So my friends and I go to a bar, and I see her making out with some random dude, which really pissed me off (not sure if she saw me). As of now I'm definitely not texting her first and have no idea what to do. So please tell me what in the hell is going on with this girl.
Also should I continue to talk to this girl? I am really attracted to but I just don't want to waste my time.