<human>: In the beginning of summer I went to a party and hooked up with this girl that I just met. We talked about our personal lives and some of our past troubles. She saw how I apparently changed my personality when I talked to different people and got mad. 

Mind you I have never gotten with a girl...

I see her in a room alone, we start talking, and I apologize but really not understanding why she got so upset. We talk for a bit and then we make-out and I cut  it short and feel guilty.

I was in shock and surprised that this just happened and go downstairs. She starts to get close to me and I end up leaving with my ride back home. The next day I text her and she wants to make something out of this.

I was not ready for it and tell her I can't.

Now I sometimes regret my decision and want to be with her; but sometimes I don't want to get her involved in my life. Also, she said would stick with me through tough times and I need/want her. What should I do?

Can you summarize the given text in a few sentences?
<bot>: My first hook-up and then rejected this girl. Now I regret it sometimes and other times I don't. What should I do?