I understand your explanation. Your symptoms are different from mine in that you are being woken from sleep with them whereas I only get mine as I am falling asleep. Its good you have had heart tests as rarely heart failure can give similar symptoms but that would have been picked up straight away in the tests so great news all was well. the other explanation could be panic attacks in the night. I have read on here alot of time about night time panic attacks in other people and they describe symptoms like yours.
Have you talked to your GP about this possibility??
I totally sympathise with your lack of sleep and also fear of sleep.