I'm sorry that you are afraid and confused.
Well, my opinion is that love is the ultimate thing. You could marry a perfectly healthy man, and he could walk out his front door and get hit by a bus, and be a parapalegic for the reat of his life. But, if you love him, you would care for him wholeheartedly.
If you didn't really deeply love him, his care would be nothing but a burden and a thorn in your side.
You are walking into a relationship where you already know these things, and don't need the what-ifs. But, if there is true love here, that comes first and all other dreams and hopes fall into 2nd place. I may be wrong, but as someone else here also said, it sounds like you may love this man in a way, but are not yet in real love.
I don't fault you for coming here and asking. That is what dating is after all, and you're not engaged I presume. You're just trying to inform yourself, and that's good.
I would give this a little more time. There are some major stresses to life with CF, but remarkably, some people with it are among the most incredible you'll ever meet. Be fair to him, and don't prolong something if you have major doubts.
Again, whatever baggage and burdens you BOTH have, they all become just part of life when you truly are in love with a person.
If it doesn't feel right, it probably isn't.
Christian