Please help me out! I wanna be frien with him but not as a girl friend.?

i broke up with my boyfriend 3 months ago. Now i am kinda seeing this guy, nothing really happens yet, we have not kissed, held hand or hugged each other, because i didnt give him a chance to get close to me physically. We go out for dinner, lunch, coffee, talk on the phone, make plan. He is really interested in me, i can tell that from the way he treats me. However, I feel i still hung up on my ex in a way, i am working on moving on. However, with this new guy, my feeling for him is so unstable, one day i like him, next day i dun have feeling for him at all. He is a very nice guy, but i am only comfortable when he treats me as friend, when he start acting like we are in relationship, i got totally freak out.i duno how i should handle this, i am afraid that i wont be able to get someone else if i let this guy go. But i got a feeling that i am not interested in him as a potential bf/gf relationship. I am so confused.if i tell him the truth how i feel,he may stop being fren wif me.