Confused, please help? Sorry, it's long.?

Alright. Last night my girlfriends sister had a party for her birthday. A lot of people showed, it was from 6-10pm. Great night, nothing could make it better til something did. My girlfriend got there (home, where the party was) around 7:30pm. I've been with her going on 8 months. Before we dated me and her best friend had something going, we'd talk everyday, flirt, laugh, her and I were almost in love, if we weren't already. Currently, she has a boyfriend and I have a girlfriend. She came over to the party upset about him controlling her and telling her not to go, buy the way the ages between us for range from 16-18. We were all sitting by the fire, she was sitting next to my girl and I was sitting at a picnic table about 10 feel away. Her and I were texting, I was telling her to enjoy herself at the party. Than that lead into deep eye contact and flirting. My feelings for her haven't changed at all. Getting to the point, it was time to go home. My girl, her friend and I were in front waiting on my ride. I had a "headache" so I asked my girl to get me a pill. She did, and in that time, I asked her friend for a kiss. We kissed, not just a lip kiss done, but we kissed. Not making out but open lip. At the time of the kiss, everything was still, nothing mattered no one was visible but her. Everything stayed still. I was happy, because there wasn't fighting and arguing like my current relationship. That night, she spent the night with my girl. After my girl went to bed, her friend and I talked, late. Like 2 hours, til 4 in morning. We caught up on a lot. We started texting this morning, but she has work. She ALREADY got into an argument with her current boyfriend. She told me she didn't know how much she missed me til we kissed. Why am I feeling like this, is she leading me on. Oh, and she said she still loved me, and calling me her bay. Please, I need someone to read this!