Hi jamiii,
I certainly understand where you're coming from. Like Nanners and others, there is definitely a grieving process involved. Having a chronic disease with no known cause and no known cure is understandably a hard pill to swallow! I didn't even really believe I had Crohn's for many, many years, until I could no longer deny it due to all the test results pointing to the same thing---Crohn's!
And like others have said, grieving can go through cycles throughout one's life.
I've decided that the best way I can live my life is to take ONLY one day at a time, and to deal with my Crohn's issues (and actually ALL issues, for that matter) as they arise. And trying to live in the present moment, know also that tomorrow may be a better day.
Hang in there!