Night at Hopiekins house!

So my friends and I ( Anna, Kaitlyn, and Kayla) were planning on spending the night at Anna's house, but we ended up going to Hope's house. We invited our other friend Trevor, who brought his friend Justin. My friend Anna is seriously obsessed with Trevor, and the other two have already dated him. I was sitting next to Trevor when Kayla pulled me into Hope's room and locked the door. She then began asking why I was all over him (which i was not, she and the other girls had their arms around the guys shoulders and were basically annoying the heck out of them, while I was just talking to them) and basically called me a slut. (which I am not.) I went back out to the couch and told Trevor to scoot over and told him that we were going to make Kayla angry.( i told Anna of this plan too) So we were right next to each other and i put my head on his shoulder. Then the probably worst thing that could have happened did. I started to like Trevor. We talked all night, and went swimming with everyone else. Anna, Kaitlyn, and Kayla walked off so Hope, Justin, Trevor, and I hung out in the pool for over another hour. I really thought Anna was going to be REALLY angry at me, but later when Trevor left, and I talked to her, she gave me permission to date him; and told me the only one angry at me was Kayla. Which made basically no sense, as she has a boyfriend and is always saying nasty, mean things about Trevor. Confused much? Yeah. I think Trevor likes me back, should i go out with him and chance that Anna is not over him, or just let it go? (which i really dont want to do)