Is he playing with my emotions or is he serious?

I know this is long but if you would kindly take your time to read all of this. I feel like you need to know the whole story. Thanks :D

Sometime during late September of last year, I met this boy that was in my gym and guitar class. We started to talk and I developed a crush on him. My gym class was switched so we were not in that same class anymore and in guitar, he sits all the way in the back. We were still able to talk because we both sit outside for about one or two hours waiting for our parents to come pick us up. He told me about his girlfriend and how she is shy around him and they barely talk. He told me that the main reason that he asked her out was because people told him that when he talked to her for the first time, she was telling everyone and acting excited. He said that he wanted a girlfriend that he could easily talk to for long periods of time. I also became good friends with his twin brother. His brother asked me who I liked and I told him that I liked his brother. The guy I liked later told me that he and his girlfriend broke up but while they were still going out, he used to arm wrestle with me then when we stopped he would still hold my hand and lock our fingers together then look me in the eye. I felt bad because it was like I broke them up. We both argue a lot because we both like being right and getting the last word. When we had a sort of big argument that was serious this time and not just flirty, he would flirt with other girls when he sees me around and ignore me so I started flirting with his twin brother in front of him. One day when it was only us outside because his brother had football practice, he told me to come sit next to him on one of the benches. There was kind of an awkward silence then he told me that he loved me. I thought he meant as a friend so I said it back. He took a deep breath then asked me if I liked him or his brother. I said that I didn't like his brother and he said if I liked him. I was going to lie but I decided to get it off my chest so I told him I did. He said he liked me too and if I could come inside with him to his locker. When we got there he kissed me and I tried to kiss him back but...I don't know why I couldn't. He just ended up touching me and kissing my neck. After that day, he sort of started to ignore me and he started flirting with one of my friends, who developed a crush on him. I was hurt but got over him. Now, I think he is trying to get me back. Today he kept trying to get my attention away from one of my guy friends who I was flirting with. And yesterday he came up to me and said that I looked really pretty. I'm not sure if I should give him another chance and trust him. I already put my heart on the line once for him. Any advice would be greatly appreciated. Thanks for taking the time to read this :D