What should I do about this guy?

Well my kinnda friends boyfriend whom is my friend and lives next door is starting to flirt with me alot more like sexually and he'll lay on me and talk about sexual things and tease me about things and sits with me on the bus he's been my friend and he use to just talk to me Like a normal person but now he's starting to act like that. He flirts with alot of girls even infront of he's girl friend but It just seems werid now to me also like when I was on the bus one day he like kept squshing me nvm maybe I'm over analyzing it I'm pretty shore he's just trying to be my friend. But what so you think?