Hey! I'm sure it must feel like a never ending chain of thoughts and you find it difficult to come out of it. It can be severely frustrating and negative if not addressed. If you could seek a little help from a therapist, in understanding the underlying belief and making a shift in the thought, that'll help you a long way.
Next Steps
book a session with a counsellor and take the gear of thoughts back in your hands.
Health Tips
instead of asking the question "what if this happens", you might want to ask "how can I make a better sense of it. Or what can I do if this happens".