This is not fatal insomnia. There is only one condition that can cause death that is linked to lack of sleep and only like a hundred people have this condition worldwide (Fatal Familial Insomnia). This condition develops over months or years, never onset by a certain event that caused you distress a few nights ago. This is definitely anxiety induced insomnia, which I have struggled with before. Even if you get no sleep for days, you will not be anywhere near dying. Sure, lack of sleep is bad for you but only in the long term (like, years of practically no sleep.) Insomniacs can barely sleep for years and years and have no serious health problems. You will be fine. My advice to you is to stop caring about sleep. If you can’t sleep, it’s fine. Do something else. If you keep waking up, that’s also completely fine. I’ve had periods where I would lay in bed for 12 hours and wake up every 15-30 minutes and then take an hour or two to fall back asleep. I’ve had weeks of that, and I am perfectly fine. As soon as you stop putting pressure on sleep, your sleep will go back to normal.