thanks cel I do think thats the best way but I have say do NOT say what clispin said,sorry clispin but if you just tell someone your not interested in them and they are crushing you and you just dashed their hopes there is no way the two you can ever be just friends.
thats sucks I know but as friendly as you might be they are not going to change their feelings over night and now they resent you even if they dont say it,and honestly you will never fully feel comfortable around this person and you'll just have to have this conversation again down the road.
save you both the heart ache..dont be friends!