how do I make him stop?

okayy long story. umm my besties big bro. 18. im 15. he has been comeing at me for too years. it all started when he found out I was cought in bed with this guy.. anouther losng storry. anyways… I kept telling him no. but what can you say he was hott. we only kissed and stuff. you know 4 play. like every time I stayed the night he would drag me in his room… a year later him g/f moved in with him. I thought it would stop but it didnt. he would text me and stay over at my house? then his g/f got prego. but it still didnt stop. I stoped doing stuff with him as soon as his g/f came tho. me and his g/f became goood friends. we has a lot I comon. wich was weiord. so hear comes the baby. looks just like him. I tell the daddy that his kid is my boyyfriend. so when he text me I ask how is my b/f he tels me ohh im good! so one day his g/f is crying to cause he can be a jerk them she tells me that she used to get mad when me and him would text all the time. this guy tellls me he likes me? what im asking is does he??? do you think his g/f knows?? one time he smacked my butt and then she came down the hall. but I don’t know ir she saw. but his guy gets jeouls when im dateing someone. I don’t know what to do I kinda like him… this one time him and his sis were steying at my house and me and him were watching tv and fell a sleep holding hands. it was sooo cute. as much as I like it how do I make it stop. its not like I cant see him cause we are kinda like family plus we are really close. we can talk bout anything. but I want the … to stop.