I'm very confused (girl situation, long)

[BWebb]

I don't post girl issues often here in OOT, but this one has me completely confused.

Background:
I've worked with this girl for awhile but never really talked to her as we were in different locations. However, the company just opened a new building that had us moved into the same building on different floors (this is a not a big company, only 4 people in her department). We talk and seem to hit it off. Last weekend our company had a bus trip to the Giants game and I had two tickets. I asked a girl to go originally but we stopped talking so I needed someone to go with. I end up asking this girl since she knows a lot of people going already and she agrees. We seem to have a very good time, this isn't just me saying this, she has told me several times since then that she had a great time.

Today

We continue to talk and go to lunch today and again seem to have a very good time. She is graduating college tomorrow and asks me to go. I say sure as other friends are graduating so why not. She also tells me she is drinking tonight and to call her later. I do and she invites me over to her friends house where she has been drinking for awhile. I get there and she is drunk but not completely wasted. The house is a friend of hers (a guy if it matters) and the only other person there is some girl passed out on the couch named Tina. She continues to drink and I start to, getting an okay buzz in the process. We are on the patio, but we eventually get inside alone together (her friend woke up and was on the patio as well). We are talking while I'm getting another beer when she tells me that "I should hook up with Tina". I am like WTF? and ask her if that means we aren't going to hook up. She starts with the I'm drunk, I don't know what I'm going, I need to go back outside. I am very confused and have no idea what to do. I finish my beer, say goodbye to those there and leave. Can anyone tell me WTF just happened?

Cliffnotes
Thought I was seeing this girl until she tells me I should hook up with her friend.