What should I do about this??

Ok I pretty much grew up with this kid, I’ve known him almost all my life. We were always friends through middle school/high school etc, and it was obvious we liked eachother but never did anything about it. Well he moved out of state about 2 years ago. In september, I show up to the first day of classes and whos sitting there in my class but him. I was soo shocked (and happy) and he says oh I moved back a few weeks ago I was hoping to run into you because you changed your # and I didnt have it anymore. we talked after class and so on…well since then after every class we always hang out for a little bit, just talk, maybe watch a movie nothing serious. Well tonight he was acting weird so I asked whats wrong and he goes..I like you a lot and I’ve wanted to be with you for a while, but the thing is I have a girlfriend. (she lives an hour away). I kind of backed off after hearing this, I was annoyed because I had told him back in september that I had a boyfriend (I’ve been with my boyfriend almost 4 years, but we’re “not talking/taking a break” or whatever right now…needed some time apart) why didnt he tell me in the first place?? Well he noticed I was irritated and has not stopped texting me for the last few hours just saying stuff like..I hope I didnt blow it I really like you please dont hate me blah blah blah…I think were both stuck in a confusing mess…so I guess my choices are to either not talk to him anymore…I dont want to interfere with his girlfriend…or to go with the flow and see what happens? whats my best choice at this point sorry its so long =)