I love you...by surprise

I think if you don't feel the same to him you must end up the relationship. Tell it to him honestly that you don't have the same feeling for him than to lie to him. If i was him i will like to hear what is true so i can easily move on in my feelings for you than to make be believe in something which is not true. I would be more glad if i will know the true at the first time.

If it is happened with me then i was shocked for some minutes... But then can realize his feelings and if it is really love then i surely agree with him.....

Tell them exactly that. It will probably upset him, but it's better than saying you feel the same, then he later finds out you lied to him.