Help! I don't know what to do. How would you deal with a bf/gf with severe medical problems?

So, you are probably going to think that I am a totally heartless b***h after this but.... I just found out that a guy I was interested in has cystic fibrosis, diabetes melitus, and has also undergone a liver transplant. Cystic fibrosis is a hereditary condition, and I am afraid that if I get involved with this person that I would not be able to have children with him for fear of ping on the disease. Also, the life span expectancy for people with the condition is generally shorter than most others. And, coupled with his other conditions, I am terrified that I would be waiting for the day to come when I would have to bury him rather than looking forward to growing old with him. I feel terrible... but, I just don't think I am strong enough or brave enough to deal with a partner who has so many health concerns. What should I do?