From experience I understand the hesitancy in telling people that I have Cf. Not because I was afraid of losing them but because I never ever wanted anybody to feel sorry for me. CF is a part of who I am and who you are. It is just the same as being white or black. Ive learned that when you tell people there is the initial shock and quite often they are very hesitant in what they say and honestly, half the time they dont know what to say. You just have to find the people that matter and who dont care that you cough and hack all the time. And as for not telling your boyf. I am 17 and I have an amazing boyf who supports me in everything I do. Youd be surprised at how someone who likes you will react.
But if he breaks up with you don't be down, in the long run if he runs whens things get tough you don't want a guy like that. But you're only 13, Trust me when I say this, There will be PLENTY of boys.