We don't always know why God lets some things happen to us; He sees the whole picture, while we seldom do. Sometimes we're even like Jesus' disciples, who "did not understand any of this. Its meaning was hidden from them" (Luke 18:34).
But God may have allowed this to happen to you for a very important reason: to convince you that you need God. Elsewhere in your letter, you admit you've always been a strong, self-sufficient person, and as a result you've never felt any need for God. Perhaps you thought God was only for weak people, so you didn't think you needed Him. To put it another way, your pride has kept you from God.
Instead of being angry with God, you should be grateful -- grateful for the years of health He gave you, and grateful especially that He has now given you a second chance. You were on the brink of eternity -- and God pulled you back and has given you another opportunity to come to Him. The Bible says God "is patient with you, not wanting anyone to perish, but everyone to come to repentance" (2 Peter 3:9).
Don't face the future without God. Instead, by a simple prayer of faith sincerely ask Christ to come into your life. Even if you never regain your physical strength, you'll have something far more valuable: the spiritual strength to face the future with the hope and peace that only come from Christ.