If you have made it to 28 without too many problems, you should be able to live to a ripe old age with aggressive treatment of your CF. I myself wasn't diagnosed until I was 29, and by that time my FEV1 was 81%. It's has varied with the different doctors I've seen, but my latest test a month ago it was 79%. My current doctor that I've been seeing for about 2.5 years is extremely aggressive and has me feeling better than I have since way before I was diagnosed. Of course, it is a pretty big commitment doing what needs to be done (nebs, physio, IVs) but you're worth it and you're family is worth it.