I can understand your fear--it's really hard to keep trying something when you have a fall. You are really brave to get back into biking after not doing it for 40 years, and that is to be applauded! I don't have any really great suggestions, other than just to be gentle with yourself and not beat yourself up for how you are feeling, but at the same time stay committed to doing it. Just approach it steadily and work with yourself bit by bit that way--that is how I have dealt with scary things myself. You are awesome for doing what you are doing, between the exercise and the weight loss--that's really incredible, so give yourself credit!
Best of luck!