Am confused: S:S:S.....

I have know this lad for nearly two years I have never thought of him of anything else I have always said he's a friends and nothing else. We always argue all the time none stop we may have a few days which we will be nice to each other but we always end up arguing about something, I found out that he liked me and that made me resent him more and I was acting really funny with him for a while in till I found out he didn't like me anymore. Then one night he had a party when he got drunk he comes on to me more but I had a lot to drink as well then I was lying on the floor and he came lying down next to me, I couldn't really remember that night but he told his mate that we was just talking and we was looking at each other and we both moved towards each other. That night we just kiss for a while and when he walked me home I turn to him and said will you promise me that nothing will change. We didn't see each other for a week and when we did things was a bit funny at first but then I try not to make it uncomfortable and acted my self. Since that night I haven't stopped thinking about him every night I just thinking about him but when I was with him he just annoys me what ever he does then some days I just want to be with him and I get butterflies all the time. Am really really confused because I can't stop thinking about him but I don't want our friendship to be ruined we are too good as a friend for it to be ruined. Please help me !!