Bestfriend not my boyfriend

Ok so me and my bestfriend had  hooked up a couple of times  he doesn't tell me he likes me straight forward  but I'm guess he must since we hook up I have a boyfriend yeah I know that wasn't right but it's done can't change it I have feelings for my boyfriend  but just everytime I'm with my bestfriend it's get a little more then just bestfriends.  How so I ask my bestfriend how he really feels without making things awkward ???