Trauma
No one I know really talks about memory gaps due to trauma, but most of my family has them. The two main ones for me are when I was six, one of my older brothers was dying of leukemia, and the other was in 2020, when my dad went insane.
It honestly is a terrifying feeling to have literally months of your life be blank. My family doesn't really talk much about what happened with my brother (he is alive and doing well by the way), but recently it has been up for discussion. I have discovered that almost a year of my memory during that time is missing: I mostly remember people crying (especially my baby sister) and visiting the hospital several times.
But the most terrifying time of my life was probably when my dad went crazy.
He hadn't been mentally stable for years, but we hadn't realized anything was off. (He mostly sat around like a rock and did nothing.) We discovered that he was crazy when he was on a trip with my oldest brother about halfway across the USA from us. My brother ended up calling 911, and when they made it back home we found out that my father was Bipolar.
It is a really terrifying feeling when you realize that you have a dad, but he doesn't do anything a dad should do. My dad is pretty normal now (he still gets kinda weird sometimes), and I simply am not used to it. If I am going to be honest, I and most of my siblings no longer have a good relationship with our dad. For too many years he didn't care about us, or what we did, and I simply don't have the level of respect for him that I should have.
I have a memory gap of several months, and only recently have I opened up to several people close to me and let some of the trauma go. I've kept it locked inside of me for so long, and I don't really know how to let go. I am afraid of letting people see my vulnerable side, and I'm afraid of building a relationship with my dad because I'm afraid that he will go insane again.
So I guess for me, the most terrifying experiences of my life are from when I went through trauma, and I'm afraid to go through that again. I'm slowly healing, but I've got a long ways to go.