My bestfriends boyfriend says he likes me :S?

I don't know what to do, I only see him as a friend and that's all I ever have been to him, I would never do anything like that to my bestfriend or anything. But last night he says he likes me in that way. I dont know what to do, he says he still loves my bestfriend. But I just don't know what to do or say to him. It feels like I'm being suffocated by boys I don't like, I'm to friendly and find it hard to turn someone down or say no, I don't lead them on I just become distant hoping they get the picture. Can someone please help me learn how to be a more stronger person when it comes to these things?