Confused?!

I really like this guy who's 19 and In college and my friends are telling me stop texting him and being friends and hanging out with him and everything but it's hard because we have had sex. I'm not sure what to do. :( confused and questioning a lot. I'm 18 and I will be a senior this year. They're telling me he's taken but he's never told me he's taken? Wouldn't he stop talking to me if he was taken?