I can't tell you much from personal experience--I've gotten to weird body sensations, but not all the way to SP--but when I get scared, I have invoked help from some unseen entity that is meaningful to me.

If you're religious, that could be God or Mother Mary or the Buddha, or what have you, and if not, it could be your beloved grandmother in heaven or departed pet, for instance. You could say, "Are you there? Do you think everything is going to be OK? Will you stay with me while I do this?"

I tried this a few days ago when I thought I was approaching SP and got a bit freaked out, and it was quite comforting.