Are you in general afraid of stepping out of your comfort zone? Traveling alone, trying new things out, etc?
I speculate that the two are related. At some point you have to trust the process and make the resolve to try and stop to control the situation and just see how it unfolds. To take a leap into the unknown.
To give you a travel analogy, once you've done your research and the place you're going to seems reasonably safe, millions of other people have been there, etc etc, there comes a time when it is counterproductive to worry about the stuff. You cannot predict what will happen in any more detail (and that is part of the fun!).. at some point you have to say, "ok, I've got the tickets, I have emergency money if things go south and I'll have accomodation", and just go for it.
How does this relate to your ayahuasca terror? Simple - You've made the decision to be there, presumably you want to explore these realms .. just accept that you may be a bit scared, for most people (yours truly included) going into the unknown can be a source of anxiety and uncertainty, but presumably the benefits far outweight the risks, or there would be little point to it.. so if you get yourself in that situation, there comes this point as said above, where you have to just let go.
It will seem weird because it's new and you couldn't imagine it. You may feel threatened because you can no longer predict your environment. That is all normal and even optimal (it's a survival thing).
Where this process stops being your friend is when you let yourself freeze with fear, and to add insult to the injury the analogy with traveling breaks down at this point, since under normal circumstances you cannot abort the trip.
There has to come a time when things are just getting very weird where you tell yourself, "It's ok. I've come here to explore, lets see where this ends up". Most likely you'll find there was nothing substantial to fear in the first place.
Good luck with your travels:thumb_up: