I was in a simillar situation, except i lived with the guy as he has been my flatmate for 2years. I knew he liked me, and like in your situation, he treated me so well and helped me get over an bad break up. One night we drunkenly pulled, and it clearly meant more to him than me. But then we kept pulling on nights out and eventually I agreed to go out with him due to pressure from other flatmates. However, it did not work and after 8 months of trying to make it work cos he is such a good guy, I had to end it.
Just be honest with him, explain that u love him but u are not 'in love' with him. Say he will always be a good friend and you understand if he needs time to get used to it.
2months later, after doing this, I had my best friend and flatmate back and we have never been happier.