The most important thing I can tell you is that God knows all about your situation. He knows the uncertainty you're facing, and He also knows your fears. But most of all, He loves you and wants to help you deal with this by learning to trust your future -- and your whole life -- into His hands. Can anything be more important?
After all, if this condition had never been diagnosed, you might have gone through your entire life without ever thinking seriously about God, or about eternity. But eventually we all die, and some day we all must enter eternity and face God. But then it will be too late to prepare our souls to meet God. The Bible warns, "Man is destined to die once, and after that to face judgment" (Hebrews 9:27).
This is why I urge you to turn to Jesus Christ and trust Him alone for your eternal salvation. Only one thing separates us from God, and that is our sin. But Jesus Christ came into the world for one reason: To take upon Himself the judgment we deserve. By His death on the cross and His resurrection from the dead He made our salvation possible. Ask Him to come into your life today -- and He will.
But Christ also wants to help you right now. He wants to calm your fears and give strength for your life every day, no matter what the future holds. We are never alone when we know Christ.