You need to tell him exactly how you feel. If you are unfulfilled, you will not be doing any justice to him. Tell him and you both need to move on. He will be hurt but he needs to know.

its a tough decision ):
i happened to be in a very similar one.
its like some days you love him, and other days, you dunno how you feel.
keep living your life, but when you get a certain strong feeling towards him - no matter good or bad, TELL him. if he still loves you, he will understand, and depending on what type of guy he is, he may react differently.
if he's a kind-hearted and understanding boy, he'll soon be thankful and respectful of your honesty.

u have 2 tell him how u feel it might help u