Ok, this is not helping..this is the fear talking.
It's okay to be afraid! This IS scary-- make no mistake. Life is scary, and loving someone is scary, because you might lose them. Yes, you're afraid of losing him... that's realistic. But if you withdraw now, you've ALREADY lost him, kwim?
Facing the fear and feeling it will NOT kill you. You can't be positive and upbeat ALL the time. You can't fight the disesas every single minute of the day. Everyone has dark nights-- but SHARE them!
Millions and millions of couples have gone through health crises together... if they can get through it, you can get through it. Do it one day at a time and face whatever is right in front of you. You can get through anything one minute at a time-- together.