How should i show/tell my best friend I love him?

I'm bi-curios and I'm in love with my guy best friend. We treat each other as brothers. I'm 2 years older that him. The 2 of us get really close to each other, we even wrestle and tickle each other almost all the time. we like holding each others hand while walking and he doesn't care if other people see us holding hands. One time we almost kissed each other but we were disturbed by someone then the both of us blushed. When I'm doing something across the room he would always look at me and when I catch him looking at me he would look the other way but sometimes he would just stare at me for 5 seconds and I would notice his pupils dilate. How and should I tell him that i'm in love with him? If i'm going to kiss him should I just kiss him without asking or saying something? Please I need detailed advice.