I feel like I am falling apart, can anyone give me advice

I am falling in love with my best friends brother. First off, she does know and understand. When I first met Josh there was something different about him, something that immediatly drew my attention to him, weird part is that it wasn't his looks. The more time I spent around him, the more I couldn't handle bein away from him. Josh is too old for me right now. I am sadly underage. So that is were many problems start. We connected from the very begining, we have been ourselfs from the start. We are very comfortable with eachother. One night I was sleepin over at my friends house, she fell asleep so Josh and I went on a walk, when we got back it was about 2am. We talked for 2 hours about the most pointless and random stuff, but we loved it :) We definitly enjoyed eachothers company. So for the first time he kinda hinted that he was interested, but in a playful way. 3 days later we went on another walk. We stopped walkin for a bit and sat down, we sat hip to hip, it was very hard to keep from kissing eachother, so I got up and said, alright lets keep walkin, to make a long story short we ended up walkin in a circle, so we just sat back down, I shoved him for some reason, we were just playin around, so he told me he deserves a kiss on the cheek, :) I thought he was kidding, but I moved in close to his face, I intended to just tease him and move away right as I got close enough, but he caught me by surprise, he turned his head right as I got close enough & waited for me to kiss him on the lips instead. It was actually adorable. But I felt unsure