My bestfriends 21 year old brother likes me?

Well I'm only 15. And I think my bestfriends brother likes me. So today, I was over at my bestfriends house and her brother was there. We were all in his room and messing around on chat roulette and he was like looking at me funny because I was just kidding with some of the guys and like blowing them kisses and stuff and he was like "damn" and then he'd be like "look at this beautiful girl" an all this. So that happened and somehow my friend had to leave the room and he hurried up and shut the door an Locked it after she left and like started hugging me and it was really awkward because it was just me and him in the room so I tried to leave and he hugged me tighter and was like no yOur not going anywhere. I ended up getting free and opening the door. Later on we were still on chat roulette and he kept grabbing me by the waist and and stuff. After that we were still in his room watching a movie and me and my BFF were on his bed and he tried kicking my bestfriend off and laying with me. He ended up on the floor but he was blowing me kisses and winking at me and trying to grab my hand and stuff. He would also only offer me things and he'd want me to do things with him instead of my BFF. And he also wanted to drive me home but just him and me. He didnt want my Bff to go. This isn't the only the he's been like this. He has done stuff like this for a loooong time. I'm not saying I like him or anything but I just need some advice. It's kind of uncomfortable for me and I don't want my BFF thinking anything.